Solid-State Synthesis of Germanium Nanocrystals from a Chloride
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Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2019 Solid-state synthesis of germanium nanocrystals from a chloride-derived germania glass and colloidal synthesis of germanium nanocrystals from germanium halides with trisilane Yujie Wang Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Chemical Engineering Commons Recommended Citation Wang, Yujie, "Solid-state synthesis of germanium nanocrystals from a chloride-derived germania glass and colloidal synthesis of germanium nanocrystals from germanium halides with trisilane" (2019). Graduate Theses and Dissertations. 17118. https://lib.dr.iastate.edu/etd/17118 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Solid-state synthesis of germanium nanocrystals from a chloride-derived germania glass and colloidal synthesis of germanium nanocrystals from germanium halides with trisilane by Yujie Wang A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Chemical and Biological Engineering Program of Study Committee: Matthew G. Panthani, Major Professor Nigel Reuel Javier Vela The student author, whose presentation of the scholarship herein was approved by the program of study committee, is solely responsible for the content of this thesis. The Graduate College will ensure this thesis is globally accessible and will not permit alterations after a degree is conferred. Iowa State University Ames, Iowa 2019 Copyright © Yujie Wang, 2019. All rights reserved. ii DEDICATION This thesis is dedicated to my family and boyfriend for their love and support. I’d like to thank my parents Guanghui and Huazhi, my boyfriend Weihao, my brother Peiyu, my sister Yulong, my sister-in-law Lingling, and my nieces Jiaye and Jiaxuan. It’s your unconditional love that gives me the strength and confidence to overcome any challenge. iii TABLE OF CONTENTS Page LIST OF FIGURES .................................................................................................................. v ACKNOWLEDGMENTS ....................................................................................................... ix ABSTRACT ............................................................................................................................. xi CHAPTER 1. INTRODUCTION ............................................................................................. 1 CHAPTER 2. REVIEW OF LITERATURE ............................................................................ 4 CHAPTER 3. SYNTHESIS OF GERMANIUM NANOCYRSTALS FROM SOLID-STATE DISPROPORTIONATION OF CHLORIDE-DERIVED GERMANIA GLASS ...................................................................................................................................... 8 3.1 Experimental Methods .................................................................................................... 8 3.2 Characterization ............................................................................................................ 10 3.3 Results and discussion .................................................................................................. 12 3.4 Conclusion .................................................................................................................... 19 3.5 Acknowledgements ....................................................................................................... 20 3.5 Supporting Figures and Tables ..................................................................................... 20 CHAPTER 4. COLLOIDAL SYNTHESIS OF TIN AND GERMANIUM NANOCYRSTALS AT ROOM TEMPERATURE ............................................................... 30 4.1 Experimental Methods .................................................................................................. 30 4.2 Characterization ............................................................................................................ 33 4.3 Results and discussion .................................................................................................. 34 4.3.1 Sn nanocrystals ...................................................................................................... 34 4.3.2 Ge nanocrystals from GeI2 with oleylamine .......................................................... 37 4.3.3 Ge nanocrystals from GeI2 with octylamine .......................................................... 43 4.3.4 Ge nanocrystals from GeCl2 with octylamine ....................................................... 53 iv 4.4 Conclusion .................................................................................................................... 59 4.5 Acknowledgements ....................................................................................................... 59 CHAPTER 5. CONCLUSIONS AND FUTURE WORKS .................................................... 60 5.1 Conclusions ................................................................................................................... 60 5.2 Future works ................................................................................................................. 61 NOMENCLATURE ............................................................................................................... 62 REFERENCES ....................................................................................................................... 63 v LIST OF FIGURES Figure 1. XRD patterns of hydrolyzed GeCl2·dioxane before and after annealing at various temperatures. Cubic Ge reference: PDF # 00-004-0545, hexagonal GeO2 reference: PDF # 00-036-1463 ............................................................................................................................ 13 Figure 2. TEM images of nanocrystals obtained from hydrolyzed GeCl2·dioxane annealed at (a) 375 °C and (b) 425 °C. The insets show the corresponding FFT pattern indexed to diamond cubic Ge. .................................................................................................................. 14 Figure 3. XPS of hydrolyzed GeCl2·dioxane before annealing (a), and (b) after annealing at 250 °C. Collected data are shown with open circles. Fitted data are shown in solid curves of purple (Ge 3d), red (Ge4+), green (Ge2+), and blue (Ge0). ....................................... 16 Figure 4. (a) Baseline-corrected Raman spectra of GeCl2·dioxane precursor before hydrolysis (red) and after hydrolysis (blue). (b) Normalized Raman spectra of hydrolyzed GeCl2·dioxane annealed at temperatures between 250 and 450 °C. ....................................... 17 Figure 5. XRD patterns of annealed samples at different temperatures taken when the humidity was low (RH ≤ 20%). Cubic Ge reference: PDF # 00-004-0545, hexagonal GeO2 reference: PDF# 00-036-1463. ..................................................................................... 20 Figure 6. TEM images of nanocrystals obtained from hydrolyzed GeCl2·dioxane annealed at (a) 325 °C, (b) 350 °C, (c) 400 °C, (d) 450 °C. ................................................................. 21 Figure 7. TEM of hydrolyzed GeCl2·dioxane annealed at 450 °C. ........................................ 21 Figure 8. TEM of hydrolyzed GeCl2·dioxane annealed at 425 °C. ........................................ 22 Figure 9. TEM of hydrolyzed GeCl2·dioxane annealed at 400 °C. ........................................ 22 Figure 10. TEM of hydrolyzed GeCl2·dioxane annealed at 375 °C. ...................................... 23 Figure 11. TEM of hydrolyzed GeCl2·dioxane annealed at 350 °C. ...................................... 23 vi Figure 12. TEM of hydrolyzed GeCl2·dioxane annealed at 325 °C. ...................................... 24 Figure 13. Survey XP spectrum of hydrolyzed GeCl2·dioxane without annealing. The spectrum shows Ge, C, O and Cl. Signals assigned by an ‘*’ are related to Ge LMM. Ratio between O and Cl was determined to be 2 : 1. ........................................................................ 24 Figure 14. Raman spectra of GeCl2·dioxane acquired with (a) 2400 grooves/mm and (b) 600 grooves/mm gratings. The spectra were acquired for 10 s with a 3.60 mW 532 nm excitation laser. The Raman peak assignments and vibrational modes can be found in Table 3.1............................................................................................................................................ 25 Figure 15. Raman spectra of GeCl2·dioxane before and after hydrolysis. The OH stretching vibrational mode is shown at 3510 cm-1. The spectrum was collected for 10 s with a 3.60 mW 532 nm excitation laser. .................................................................................................. 26 Figure 16. (a) Annealing temperature dependence of Ge-Ge LO phonon (a) Raman peak position and (b) full width at half maximum (FWHM). As the annealing temperature increases, the Ge LO phonon peak is shifted to higher wavenumbers and the FWHM decreases. The patterns are consistent with quantum confined excitons in nanocrystals of increasing size.42 The uncertainties represent standard deviations from five spectra collected at each