DOCSLIB.ORG

Applications of Charge Collection Microscopy: Electron-Beam- Induced Current to Semiconductor Materials and Device Research

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Applications of Charge Collection Microscopy: Electron-Beam- Induced Current to Semiconductor Materials and Device Research Scanning Microscopy Volume 1993 Number 7 Physics of Generation and Detection Article 16 of Signals Used for Microcharacterization 1993 Applications of Charge Collection Microscopy: Electron-Beam- Induced Current to Semiconductor Materials and Device Research Richard J. Matson National Renewable Energy Laboratory, Colorado Follow this and additional works at: https://digitalcommons.usu.edu/microscopy Part of the Biology Commons Recommended Citation Matson, Richard J. (1993) "Applications of Charge Collection Microscopy: Electron-Beam-Induced Current to Semiconductor Materials and Device Research," Scanning Microscopy: Vol. 1993 : No. 7 , Article 16. Available at: https://digitalcommons.usu.edu/microscopy/vol1993/iss7/16 This Article is brought to you for free and open access by the Western Dairy Center at DigitalCommons@USU. It has been accepted for inclusion in Scanning Microscopy by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. Scanning Microscopy Supplement 7, 1993 (Pages 243-251) 0892-953X/93$5.00+ .25 Scanning Microscopy International, Chicago (AMF O'Hare), IL 60666 USA APPLICATIONS OF CHARGE COLLECTION MICROSCOPY: ELECTRON-BEAM-INDUCED CURRENT TO SEMICONDUCTOR MATERIALS AND DEVICE RESEARCH Richard J. Matson National Renewable Energy Laboratory 1617 Cole Blvd., Golden, CO 80401 Phone No.: (303) 275-3726, FAX No.: (303) 275-3701 Abstract Introduction Among all of the possible techniques for the micro­ The many ways in which a high energy electron in­ characterization of semiconductor materials and devices teracts with matter give rise to a number of useful, ob­ in a scanning electron microscope (SEM), charge collec­ servable signatures of a sample in the scanning electron tion microscopy (CCM), more commonly known as microscope (SEM). Semiconducting materials and de­ electron-beam-induced current (EBIC), is probably both vices, in particular, lend themselves to a wide variety of the most easily deployed and the most versatile charac­ SEM-based analytical approaches. In particular: charge terization technique. Following a brief review of the collection microscopy (CCM), voltage contrast (VC), basic theory of the generation and detection of the EBIC cathodoluminescence (CL), electron channeling (EC), signals, various techniques and applications to the micro­ scanning deep-level transient spectroscopy (SDLTS), and characterization of experimental semiconductor materials scanning electron-acoustic (thermal wave) microscopy and devices will be presented. The applications are pri­ (SEAM). All of these have been reviewed in the book marily to emerging photovoltaic materials and devices. SEM Micro-Characterization of Semiconductors, edited This report is not in any way intended as a complete by D.B. Holt and D.C. Joy (1989). Of all of these overview of all EBIC related techniques or most material microcharacterization techniques, CCM may be the most or device applications. Beyond offering a short review easily deployed and the most powerful analytical tool for of CCM theory, this paper complements the literature characterizing electronic materials and devices. As a (1) as a basic introduction to CCM, and (2) by focusing practical introduction, it is the purpose of the present on the use and extension of CCM techniques for basic paper to briefly review the theory of the generation and studies in experimental electronic materials. detection of the CCM/EBIC (electron-beam-induced current) signal and then present a variety of recent extensions and applications of EBIC techniques. The terms EBIC and CCM will be used interchangeably in this paper because EBIC is the most commonly used term for this technique in the literature and in the community, although "EBIC" can be confused with elec­ tron-beam-induced conductivity and is thereby less pre­ cise than CCM (see Holt, 1974). Charge collection has Key Words: Charge collection IT1Jcroscopy (CCM), also been called the barrier electron voltaic effect and is electron-beam-induced current (EBIC), m1cro­ the least commonly used term in the literature characterization, photovoltaic, introduction. (Ehrenberg et al., 1981; Leamy, 1982; Holt, 1974; Holt, 1989). Generation and Detection of EBIC Signal When a semiconductor device is penetrated by ener­ getic ( > 1 ke V) primary electrons, the succession of scattering events, or "collisions," result in the promotion of electrons from the valence band to the conduction band, thereby producing electron-hole (e/h) pairs. Without the presence of an electric field, the electrons and holes simply recombine. If, as in the case of a 243 Richard J. Matson Scan direction a SEM ,.._________.A >------f B CRT b Figure l. A schematic illustration of the scanning movement of an electron beam across a polycrystalline device. The light lines indicate grain boundaries which usually act as recombination sites and, therefore, locations of current loss. semiconductor device, there is an electric field present within collection distance of the e/h creation, the elec­ tron and hole can be separated and collectec.l via contacts to the device. In tum, this collected current is amplified and used to modulate the intensity of the SEM CRT Figure 2. A comparison of an EBIC image (a) and the (cathode ray tube), as indicated in Figure 1. As an secondary electron image (SET) (b) of the same area of example, an EBIC image (a) and a secondary electron a MTS device on Wacker polycrystalline silicon. The image (SEI) (b) of a simple metal-insulator-semi­ areas of recombination (defects) show up dark in EBIC conductor (MTS) device made from polycrystalline images. Bar = 100 µm. silicon is given in Figure 2. The effect of grain boundaries, or other sources of recombination, on the charge collection image is evident. Wherever there is relative ease of creating such a Schottky barrier (often electron/hole recombination, there is a corresponding with the deposition of - 200 A of Au) that readily loss of collected current and, therefore, CRT intensity, extends the use of CCM to the investigation of which appears as the dark areas in the image. Note the developing electronic materials that are not yet devices. difference of the density of defects among different Considering e-/h + pair generation more closely, we grains and differing portions of grain boundaries. can calculate .0.N, the number of e/h pairs generated per Essentially, the electron beam acts as a constant, second for a given SEM beam condition, by mobile point source of current generation and can be used for "micro" -characterization, or characterization of (1) micron scale variations in the electrical properties of a material or device. where (2) Effectively, the sample itself is its own detector, and nothing other than amplification of the EBIC signal and and f is the average fraction of the energy of the incident a SEM vacuum chamber feedthrough for the signal is beam electrons lost to back-scattering [often taken as necessary to deploy this capability. Lacking an actual p­ half the backscatter coefficient (Holt, 1989)]; lb and Eb n junction in the device, the electric field required for are the electron beam current and voltage, respectively; charge separation can be provided through either an ex­ q is the electronic charge; ei is the ionization charge or ternal bias applied to the device or through the simple the average energy required to create an e/h pair; and G fabrication of a Schottky barrier device. It is the is the gain. A good value for ei is usually taken as 244 EBIC applications in semiconductor R & D approximately three times the Eg of the material (Holt, 1989; Leamy, 1982). By dividing the energy available in a primary electron for ionization by the energy re­ 1.0 quired for ionization, the gain, G, gives the factor by which the maximum EBIC can exceed the Jb, which 4 commonly runs in the range of lo'.3-10 . The practical significance of this is (a) that common Tb values of 100 pA can give rise to µA-range signals which can be han­ dled "cleanly" by most amplifiers, and (b) that even very inefficient experimental devices can still be charac­ terized quite often by CCM. In this author's experience, the lowest "clean," or useful, scale for amplifiers is the nA scale. Hence, even a 1 % efficient device and a 150-pA, 20-kV beam still leaves an adequate signal. Figure 3. EBIC line scan superimposed on an EBIC One use of the relation in equation (1) is to establish map of the defects in an epilayer of GaAs on a silicon a reference for the efficiency of the device. Termed substrate. The top line is the 100 % electron beam quan­ electron-beam quantum yield, or charge-collection effi­ tum efficiency reference line per equation 1. The bot­ ciency of a barrier, 11cc(Holt, 1989), the measured tom line is both the position of the line scan and the zero EBIC, ICC' is normalized to the theoretically generated beam current reference line. The middle line is the current, or EBIC linescan indicating the actual current loss in a defect area relative to 100% collection. Bar = 10 µm. (3) This is demonstrated in Figure 3 on an epilayer of a beam in Si, the injection levels are 1023 pairs/cm 3 /sec. GaAs-on-Si device where the atomic lattice mismatch re­ In addition, ESD processes scale directly with the charge sulted in dislocation networks. In Figure 3, the refer­ density (ibid.). In an earlier work, for example, the ence for 100 % quantum efficiency (per equation 1) is case was made that even with a 100-A, 20-kV, 50-pA represented by the top, horizontal line. The bottom line beam, the electron beam was desorbing oxygen from is both the position of the line scan and the zero beam polycrystalline CuTnSei, thereby locally type-converting current reference line. The middle line is the EBIC it from p-type ton-type (Matson et al., I 989).
Load more

Recommended publications
  • Cathodoluminescence in Semiconductor Structures Under Local Tunneling Electron Injection Petr Polovodov
    Cathodoluminescence in semiconductor structures under local tunneling electron injection Petr Polovodov To cite this version: Petr Polovodov. Cathodoluminescence in semiconductor structures under local tunneling electron injection. Optics [physics.optics]. Ecole Doctorale de l’Ecole Polytechnique, 2015. English. tel- 01346834v2 HAL Id: tel-01346834 https://hal.archives-ouvertes.fr/tel-01346834v2 Submitted on 23 Jul 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Thèse présentée pour obtenir le grade de DOCTEUR DE L'ÉCOLE POLYTECHNIQUE Spécialité : Physique Par Petr POLOVODOV Cathodoluminescence in semiconductor structures under local tunneling electron injection Soutenue le 21 décembre 2015 devant le jury composé de : M. Fabrice Charra CEA/Saclay, Gif sur Yvette Rapporteur M. Philippe Dumas CINaM, Marseille Rapporteur M. Razvigor Ossikovski LPICM, Ecole Polytechnique, Palaiseau Examinateur M. Oleg Tereshchenko Rzhanov Institute of Semiconductor Examinateur Physics, Novosibirsk, Russie M. Yves Lassailly LPMC, Ecole Polytechnique, Palaiseau Directeur de thèse M. Jacques Peretti LPMC, Ecole Polytechnique, Palaiseau Co-Directeur de thèse 2 ACNOWLEGEMENTS I have defended my PhD thesis in physics. This is the accomplishment of myself but several persons have contributed to this work. First of all, I am grateful to François Ozanam and Mathis Plapp, successive Directors of the Laboratory, who allowed me to perform my PhD work at the LPMC in the best possible conditions.
    [Show full text]
  • Low-Voltage Cathodoluminescent Phosphors a 20-Year Chronology of Low-Voltage Cathodoluminescence Efficiency by Lauren E
    Low-Voltage Cathodoluminescent Phosphors A 20-year chronology of low-voltage cathodoluminescence efficiency by Lauren E. Shea hosphors have been used for the display of information since the invention of the cathode-ray tube (CRT) by Karl Ferdinand Braun in 1897 (1). With the P development of color television, an effort spanning approximately thirty years, came the most significant advances in phosphor technology. The most noteworthy was the shift to the all-sulfide system, and discovery of the red, rare-earth oxysulfide phosphors 3+ (e.g., Y2O2S:Eu ) (2). White brightness efficiency of phosphor screens also improved significantly: 15 lm/W in FIG. 1. Efficiency of red phosphor powders (lettered squares) and screens (numbered diamonds) as a function of electron accelerating voltage. Y O :Eu - A, I, S (12); G (13); N (20); O, U, 5, 9 (14); W (21); YVO :Eu - B, L, 1951 to over 35 lm/W in 1979, as a 2 3 4 Q (13); F (18); P, X, 7, 10 (14); Y2O2S:Eu - C, J, R (22); D(12); H, Y (20); K, V (21); M, T, 3, 6, 11 (14); 8 result of new phosphor formulations (23); ZnCdS:Ag, In - 1 (16); ZnCdS:Ag, In + SnO2 - 2 (17); LaInO3:Eu - 4 (15); unspecified - E (18). and improved screening techniques (3). Today, a primary focus of research toire d’Electronique de Technologie et reported in earlier years, and (4) has in the area of luminescence is phosphor d’Instrumentation (LETI) (5). Many progress been made? development and improvement for FEDs are being designed for operation in ≤ low-voltage ( 1 kV) emissive flat-panel the 5-10 kV range.
    [Show full text]
  • Multi-Color Correlative Light and Electron Microscopy Using Nanoparticle Cathodoluminescence
    Multi-color correlative light and electron microscopy using nanoparticle cathodoluminescence D.R. Glenn1, H. Zhang1, N. Kasthuri2,3, R. Schalek2,3, P.K. Lo4, A.S. Trifonov1, H. Park4, J.W. Lichtman2,3, R.L. Walsworth1,3,5 1.Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, 2.Department of Molecular and Cellular Biology, 3.Center for Brain Science, 4.Department of Chemistry, 5.Department of Physics, Harvard University, Cambridge, MA 02138 Abstract: Correlative light and electron microscopy promises to combine molecular specificity with nanoscale imaging resolution. However, there are substantial technical challenges including reliable co-registration of optical and electron images, and rapid optical signal degradation under electron beam irradiation. Here, we introduce a new approach to solve these problems: multi-color imaging of stable optical cathodoluminescence emitted in a scanning electron microscope by nanoparticles with controllable surface chemistry. We demonstrate well-correlated cathodoluminescence and secondary electron images using three species of semiconductor nanoparticles that contain defects providing stable, spectrally-distinguishable cathodoluminescence. We also demonstrate reliable surface functionalization of the particles. The results pave the way for the use of such nanoparticles for targeted labeling of surfaces to provide nanoscale mapping of molecular composition, indicated by cathodoluminescence color, simultaneously acquired with structural electron images in a single instrument. Introduction: The correlation of light microscopy with electron microscopy offers considerable scope for new discovery and applications in the physical and life sciences by providing images with both molecular specificity and nanoscale spatial resolution [1]. However, such an approach also faces substantial technical challenges in the reliable and efficient co-registration of optical and electron images [2] [3] [4].
    [Show full text]
  • Scanning Electron Microscopy, Cathodoluminescence, and Raman Spectroscopy of Experimentally Shock-Metamorphosed Quartzite
    Meteoritics & Planetary Science 38, Nr 8, 1187–1197 (2003) Abstract available online at http://meteoritics.org Scanning electron microscopy, cathodoluminescence, and Raman spectroscopy of experimentally shock-metamorphosed quartzite Arnold GUCSIK, 1 Christian KOEBERL, 1* Franz BRANDSTÄTTER, 2 Eugen LIBOWITZKY, 3 and Wolf Uwe REIMOLD 4 1Department of Geological Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria 2Department of Mineralogy, Natural History Museum, P.O. Box 417, A-1014 Vienna, Austria 3Institute of Mineralogy and Crystallography, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria 4Impact Cratering Research Group, School of Geosciences, University of Witwatersrand, Private Bag 3, P.O. 2050, Johannesburg, South Africa *Corresponding author. E-mail: [email protected] (Received 30 December 2002; revision accepted 8 July 2003) Abstract–We studied unshocked and experimentally (at 12, 25, and 28 GPa, with 25, 100, 450, and 750°C pre-shock temperatures) shock-metamorphosed Hospital Hill quartzite from South Africa using cathodoluminescence (CL) images and spectroscopy and Raman spectroscopy to document systematic pressure or temperature-related effects that could be used in shock barometry. In general, CL images of all samples show CL-bright luminescent patchy areas and bands in otherwise non- luminescent quartz, as well as CL-dark irregular fractures. Fluid inclusions appear dominant in CL images of the 25 GPa sample shocked at 750°C and of the 28 GPa sample shocked at 450°C. Only the optical image of our 28 GPa sample shocked at 25°C exhibits distinct planar deformation features (PDFs). Cathodoluminescence spectra of unshocked and experimentally shocked samples show broad bands in the near-ultraviolet range and the visible light range at all shock stages, indicating the presence of defect centers on, e.g., SiO 4 groups.
    [Show full text]
  • Photoluminescence and Cathodoluminescence Properties of a Novel 3+ Calaga3o7:Dy Phosphor
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Springer - Publisher Connector Article Materials Science March 2012 Vol.57 No.7: 827831 doi: 10.1007/s11434-011-4938-5 Photoluminescence and cathodoluminescence properties of a novel 3+ CaLaGa3O7:Dy phosphor ZHAO WenYu1,2*, AN ShengLi1, FAN Bin1, LI SongBo1 & DAI YaTang3 1 School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China; 2 School of Chemistry and Chemical Engineering, Inner Mongolia University of Science and Technology, Baotou 014010, China; 3 School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621000, China Received July 14, 2011; accepted October 19, 2011; published online December 27, 2011 3+ A single host white emitting phosphor, CaLaGa3O7:Dy , was synthesized by chemical co-precipitation. Field emission scanning electron microscopy, X-ray diffraction, laser particle size analysis, and photoluminescence and cathodoluminescence spectra were used to investigate the structural and optical properties of the phosphor. The phosphor particles were composed of microspheres with a slight tendency to agglomerate, and an average diameter was of about 1.0 m. The Dy3+ ions acted as luminescent centers, 3+ and substituted La ions in the single crystal lattice of CaLaGa3O7 where they were located in Cs sites. Under excitation with 3+ 3+ ultraviolet light and a low voltage electron beam, the CaLaGa3O7:Dy phosphor exhibited the characteristic emission of Dy 4 6 4 6 ( F9/2- H15/2 and F9/2- H13/2 transitions) with intense yellow emission at about 573 nm. The chromaticity coordinates for the phos- phor were in the white region.
    [Show full text]
  • Application of Cathodoluminescence in Paint Analysis
    Scanning Microscopy Volume 6 Number 3 Article 4 6-30-1992 Application of Cathodoluminescence in Paint Analysis W. Stoecklein Bundeskriminalamt R. Göbel Bundeskriminalamt Follow this and additional works at: https://digitalcommons.usu.edu/microscopy Part of the Biology Commons Recommended Citation Stoecklein, W. and Göbel, R. (1992) "Application of Cathodoluminescence in Paint Analysis," Scanning Microscopy: Vol. 6 : No. 3 , Article 4. Available at: https://digitalcommons.usu.edu/microscopy/vol6/iss3/4 This Article is brought to you for free and open access by the Western Dairy Center at DigitalCommons@USU. It has been accepted for inclusion in Scanning Microscopy by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. Scanning Microscopy, Vol. 6, No. 2, 1992 (Pages 669-678) 0891- 7035/92$5. 00 +. 00 Scanning Microscopy International, Chicago (AMF O'Hare), IL 60666 USA APPLICATION OF CATHODOLUMINESCENCE IN PAINT ANALYSIS W. Stoecklein* and R. Gobel Bundeskriminalamt, Forensic Science Institute D-6200 Wiesbaden, Federal Republic of Germany (Received for publication May 3, 19921, and in revised form June 30, 1992) Abstract Introduction When solving cases of burglary or investigating Paints and their components often play a decisive ship collisions, the forensic scientist frequently has to role as evidence in solving crimes. The forensic scien­ examine several layers of paint of the same color, often tist analyzing such material must not only determine the white. As a rule, the usual microscopic and spectro­ origin of unknown paints (identification and classifica­ scopic methods [fluorescence microscopy, FT-IR (Four­ tion) but in addition compare traces collected from ob­ ier Transform Infrared Spectroscopy), pyrolysis, GC/MS jects in the suspect's possession or found in his environ­ (Gas Chromatography - Mass Spectrometry), etc.] are ment with those traces secured at the scene of the crime.
    [Show full text]
  • Dislocation Related Droop in Ingan/Gan Light Emitting Diodes Investigated Via Cathodoluminescence
    Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence Galia Pozina, Rafal Ciechonski, Zhaoxia Bi, Lars Samuelson and Bo Monemar Linköping University Post Print N.B.: When citing this work, cite the original article. Original Publication: Galia Pozina, Rafal Ciechonski, Zhaoxia Bi, Lars Samuelson and Bo Monemar, Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence, 2015, Applied Physics Letters, (107), 25, 251106. http://dx.doi.org/10.1063/1.4938208 Copyright: American Institute of Physics (AIP) http://www.aip.org/ Postprint available at: Linköping University Electronic Press http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-125162 Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence Galia Pozina, Rafal Ciechonski, Zhaoxia Bi, Lars Samuelson, and Bo Monemar Citation: Applied Physics Letters 107, 251106 (2015); doi: 10.1063/1.4938208 View online: http://dx.doi.org/10.1063/1.4938208 View Table of Contents: http://scitation.aip.org/content/aip/journal/apl/107/25?ver=pdfcov Published by the AIP Publishing Articles you may be interested in High-power low-droop violet semipolar ( 30 3 ¯ 1 ¯ ) InGaN/GaN light-emitting diodes with thick active layer design Appl. Phys. Lett. 105, 171106 (2014); 10.1063/1.4900793 Influence of dislocation density on carrier injection in InGaN/GaN light-emitting diodes operated with alternating current Appl. Phys. Lett. 102, 011115 (2013); 10.1063/1.4773588 Dependence of radiative efficiency and deep level defect incorporation on threading dislocation density for InGaN/GaN light emitting diodes Appl. Phys. Lett. 101, 162102 (2012); 10.1063/1.4759003 Improvements of external quantum efficiency of InGaN-based blue light-emitting diodes at high current density using GaN substrates J.
    [Show full text]
  • SOP Cathodoluminescence Microscope
    Identifier: Revision: Effective Date: Review Date: University of Puerto Rico SOP-004 1 02/27/2007 03/26/2007 Mayagüez Campus Geology Dept. Document No.: EXACt! - 004 Author: Miguel A. Santiago Rivera Department of Geology UPR-NSF Earth X-ray Analysis Center (EXACt!) Standard Operating Procedure for: OOppeerraattiinngg tthhee Reelliioonn CCaatthhooddoolluummiinneesscceennccee Miiccrroossccooppee UPR-NSF Earth X-ray Analysis Center (EXACt!) UPR-Mayaguez, is an affirmative action / equal X – R a y L A B O R A T O R Y opportunity employer, is operated, by the University of Puerto Rico. __________________________________________________ DEPARTMENT OF GEOLOGY F- 304 Geochemistry Facilities at Physics Building University of Puerto Rico – Mayagüez Campus 1 Revision Log Revision Effective Prepared By Description Affected No. Date of Changes Pages R-0 February 27, 2007 Miguel Santiago All New Procedure All R-1 March 26, 2007 Miguel Santiago X-rays Warning for One Pregnant and Page -11 Cancer patient 8.0 - Procedure \ 2 Operating the Relion Cathodoluminescence Microscope Table of Contents 1.0 PURPOSE . 4 2.0 SCOPE . 4 3.0 TRAINING . 4 4.0 DEFINITIONS . 4 5.0 RESPONSIBLE PERSONNEL . 5 6.0 THEORETICAL BACKGROUND . 5 7.0 EQUIPMENT . 9 8.0 PROCEDURE . 11 9.0 RECORDS . 17 10.0 REFERENCES . 17 3 Operating the Relion Cathodoluminescence Microscope 1.0 PURPOSE This procedure provides instructions for the operation of the Relion Industries, Cathodoluminescence Microscope Model Nikkon OPTIPHOT-2. The UPRM – Department of Geology has a cold cathode, CITL 8200 Mk 3A mounted on a Nikon Optiphot-2 petrological microscope available for optical CL studies. The Nikon Optiphot-2 is set up as a digital fluorescence acquisition microscope.
    [Show full text]
  • Cathodoluminescence Nano-Characterization of Semiconductors
    Cathodoluminescence nano-characterization of semiconductors Paul R. Edwards and Robert W. Martin Department of Physics, SUPA, University of Strathclyde, 107 Rottenrow, Glasgow G4 0NG, UK Email: [email protected], [email protected] Abstract. We give an overview of the use of cathodoluminescence (CL) in the scanning electron microscope (SEM) for the nano-scale characterization of semiconducting materials and devices. We discuss the technical aspects of the measurement, such as factors limiting the spatial resolution and design considerations for efficient collection optics. The advantages of more recent developments in the technique are outlined, including the use of the hyperspectral imaging mode and the combination of CL and other SEM-based measurements. We illustrate these points with examples from our own experience of designing and constructing CL systems and applying the technique to the characterization of III-nitride materials and nanostructures. PACS: 78.60.Hk, 68.37.Hk 1. Introduction Cathodoluminescence (CL) is the phenomenon of light emission from a material under excitation by an energetic electron beam. The use of CL as an image-forming mode in scanning electron microscopy (SEM) can be traced back to work carried out on the first, pre- commercial, SEMs [1]. While early applications were mainly restricted to the study of cathode ray tube phosphors and geological samples, the technique began to be used for the analysis of epitaxial semiconducting materials during the 1960s [2]. The development of the technique as a characterization tool was driven by a number of differences between CL and the analogous techniques of photo- and electroluminescence (PL, EL).
    [Show full text]
  • Assessing Color Cathodoluminescence Imaging in the Scanning Electron Microscope
    Assessing Color Cathodoluminescence Imaging in the Scanning Electron Microscope Edward P. Vicenzi1 1 Smithsonian Institution, Museum Conservation Institute, Suitland, MD 20746, USA Historically, color cathodoluminescence (CL) images were obtained in the luminoscope and visualized by direct examination, film exposure, or combining red, green, and blue (RGB) filtered images collected sequentially using a greyscale CCD camera [1]. Scanning electron microscope-based CL systems offer advantages with respect to higher spatial resolution and lower electron dose/dose-rate imaging. Despite these advantages many SEM-based CL systems output only the sum of photons of all energies to form a panchromatic greyscale image by way of a photomultiplier tube (PMT) detector. Some PMT systems are modified to include RGB filtering. Such RGB images are a useful, if simplistic, color representation of the specimen. However, these long band pass images do not necessarily faithfully represent the entire spectrum of luminesced photons in the visible. Images for this study were initially collected using a Gatan ChromaCL2. This system uses a high collection efficiency parabolic mirror and disperses luminesced light onto a segmented PMT. Sixteen PMT segments are then binned into four UV-VIS images resulting in multispectral image output (Fig. 1). These dispersive multispectral (DMS) images can be collected with pixel dwell times in the range of 100s of microseconds, shorter than CCD-based systems typically limited to millisecond read-out rates. The higher image collection speed make higher pixel density, and therefore higher spatial resolution, imaging practical. In order to evaluate the spectral fidelity of DMS CL imaging, full spectroscopic imaging using a Gatan MonoCL4 Elite was also performed.
    [Show full text]
  • Cathodoluminescence Spectroscopy Studies of Aluminum Gallium Nitride and Silicon Device Structures As a Function of Irradiation and Processing
    CATHODOLUMINESCENCE SPECTROSCOPY STUDIES OF ALUMINUM GALLIUM NITRIDE AND SILICON DEVICE STRUCTURES AS A FUNCTION OF IRRADIATION AND PROCESSING DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Brad Derek White, B.S., M.S. ****************** The Ohio State University 2006 Dissertation Committee: Approved by Dr. Leonard J. Brillson, Adviser Dr. Wu Lu ___________________________________ Dr. Betty Lise Anderson Adviser Graduate Program in Electrical Engineering ABSTRACT Electronic device performance is critically dependent on the presence of deep-level and shallow states in the electronic band gap. A uniform or localized distribution of defects throughout a device structure can adversely affect doping and carrier transport, and result in changes to device saturation current, threshold voltage, ohmic contact resistivity, and Schottky barrier properties, including leakage currents. Process-induced atomic intermixing effects at heterostructure interfaces can cause decreases in sheet density and mobility of channel layers. For the presence of all such effects, the spatial variation across a given wafer can result in significant variation in device performance depending on spatial position. Spatially-resolved cathodoluminescence spectroscopy (CLS) has been used to identify the presence of radiative point and extended defects in the semiconductor band gap produced by irradiation and processing conditions for Si and GaN-based devices. Changes in deep level emission in Al-SiO2-Si capacitor structures revealed a gradient in relative defect concentrations across the SiO2 film after x-ray irradiation, indicating interface-specific defect creation. CLS measurements also revealed changes in the near-band edge signatures of AlGaN-GaN high-electron mobility transistor (HEMT) structures subjected to 1.8 MeV proton irradiation.
    [Show full text]
  • Some Geological Applications of Cathodoluminescence
    Somegeological applications ofcathodoluminescence examplesfrom the Lemitar Mountains and Riley travertine, SocorroGounty, New Mexico byVirginiaT. McLemore and James M. Barker,New Mexico Bureau of Minesand Mineral Resources, Socorro, NM 87801 Introduction ratio of authigenic and detrital minerals (Sippel, 1968),stratigraphy, Cathodoluminescence(CL), the characteristicvisible radiation (color) siliclastic components, cementation history, and provenance (Owen produced in a mineral subjected to bombardment by electrons, was and Carrozi,1986). CL hasbeen used in paleontologyto study struc- first observed in the 1870's by Crookes (1.879).It has significant ture and chemistry of fossils (Nickel, 1'978;Batkerand Wood, 1986a). applications in petrology, although many petrologists do not utilize The CL of a sample reveals geochemical,rather than optical, var- it. Luminescencein CL is typically more intense than that produced iations in a sample, which provides important compositional,tex- by ultraviolet light (see pp. 25-30, this issue);CL is also observed tural, and structural information not readily obtained by other in mineralsthat do not luminesceunder ultraviolet light. methods. However, CL is most useful when used in conjunction Cathodoluminescence is produced by excitation of electrons in with other studies such as optical microscopy,x-ray diffraction, elec- specific chemical impurities (activators) within a crystal structure. tron microprobe, scanning electron microscopy, and geochemistry. When excited electronsreturn to their ground state, visible light may Unlike ultraviolet light, where an entire specimen can be exposed, be emitted.CL may be producedat sitesaltered by radiationdamage, CL requires a thin section or relatively thin slab, preferably with chemical heterogeneity, electron charge displacements, and struc- doubly polished surfaces.The doubly polished thin sectionsalso can tural defects (Mariano, 1976;Nickel, 1978), or by unidentified pro- be used in the electron microprobe or fluid inclusion stage.
    [Show full text]