Univ. of Florida, Univ. of Illinois, Morgan State Univ., Northwestern Univ. Purdue Univ. Stanford Univ., UTEP nanoHUB.org – Toward On-Line Simulation for “Materials and Nanodevices by Design” 1Gerhard Klimeck, Mark S Lundstrom, 1M Korkusinski, H Xu, F Saied, S Goasguen, A Rahman, J Wang 2TB Boykin, 3F Oyafuso, S Lee, H Hua, O Lazarankova, RC Bowen, P von Allmen 1Network for Computational Nanotechnology (NCN), Purdue University 2University of Alabama in Huntsville 3NASA Jet Propulsion Laboratory American Physical Society, March 22, 2005, Los Angeles The NCN: Mission and Vision To support the National Nanotechnology Initiative through: • research • simulation tools • education and outreach • web-based services “To be the place where experiment, theory, and simulation meet and move nanoscience to nanotechnology.” NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 2 Simulation is Essential for Nanotechnology Development Hint from the Semiconductor Industry: • No new devices / circuits designed without software! Problem: Simulation • Accepted nano simulation tool suite does NOT exist. Approach: • Conduct research in Modeling and Simulation of: • Nanoelectronics • Nanoelectromechanics • Nano-bio sensors • Computational science • DEVELOP and DEPLOY to nanoscience and nanotechnology community Characterization Fabrication NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 3 NCN - Research nanoelectronics: NEMS: nano-bio: switches connecting molecules…. and sensors…. electronics and NEMS to biological V systems 10.0 lipid 0.0 protein …to compact models -10.0 water ….to MOSFETs -30 -20 -10 0 10 20 30 5.0 S D Tip Position (nm) Tip position (nm) 0.0 NCN 0.0 0.5 1.0 Morgan State University - Northwestern University - Purdue University - StanDCford UBiasniversi ty(V) - University of Florida - University of Illinois - University of Texas at El Paso 4 electronics at the molecular scale Al Ultra-Scaled CMOS Gate HfO2 D S 10 nm SiO2 p++ Si ~ 2 nm ~ 5 nm D G S SWNT ~1-4nm Molecules NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 5 unifying view of small devices gate µ1 [H] ["S ] µ1 S D ["1] ["2] ! ! non-equilibrium! Green! ’s function approach (NEGF) NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 6 The NCN: Mission and Vision To support the National Nanotechnology Initiative through: • research • simulation tools (1-D transport, 3-D, Synthesis) • education and outreach • web-based services “To be the place where experiment, theory, and simulation meet and move nanoscience to nanotechnology.” NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 7 Resonant Tunneling Diode t n e r r u C 12 different I-V curves: 2 wafers, 3 mesa sizes, 2 bias directions Voltage 50nm 1e18 InGaAs 7 ml nid InGaAs 7 ml nid AlAs Conduction band diagrams 20 ml nid InGaAs 7 ml nid AlAs for different voltages 7 ml nid InGaAs and the resulting current flow. 50 nm 1e18 InGaAs NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 8 NEMO the first Nano CAD Tool originally developed at Texas Instruments t n e r r Atomistic Basis Sets u C Concepts Voltage s p p p x y z 5x d 2x spin • • • • • • • • • • • Quantitative Design, Analysis, Synthesis NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 9 NEMO Key Elements: t n e r 3 5 r u Tight Binding sp d s* C Concepts Realistically Extended Devices Non-Equilibrium Green Functions Voltage s p p p x y z 5x d 2x spin Transport / Engineering Quantum Mechanics / Quantitative Physics Design, Analysis, Synthesis NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 10 Ultra Thin Body SOI: A traditional Quantum Well? Five Atomic Layer Most basic Si (001) quantum mechanical problem: IEDM, Uchida 2nd Particle in a box! Expect / Remember: 1st • State quantization • 2 counter-propagating states • 1 bound state L " k = quantize k Schrödinger Equation E 1 L # 2 2 & h d 2 propagating E V z z 0 #ik1z +ik1z % " * 2 " ( )( )( ) = z e z e $ 2m dz ' "( ) = "( ) = states 1 bound 2 2 ! z sin k z k Parabolic "( ) = ( 1 ) state E h = * Dispersion k 2m ! ! ! NCN Morgan State University - Northwestern University - Purdue University - Stanf!ord U niversity - University of Florida - University of Illinois - University of Texas at El Paso 11 ! Quantum Wells - Special Considerations in Si Five Atomic layers Five Atomic Layer Si (001) IEDM, Uchida 2nd TB ∆ESub 1 1st Eff. mass L ΔE=150meV= 6kBT effect at T=300K k1,2=π/L 2 valleys 4 propagating states 2 bound states k1,2 envelope km fast oscillations NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 12 The NCN: Mission and Vision To support the National Nanotechnology Initiative through: • research • simulation tools (1-D transport, 3-D, Synthesis) • education and outreach • web-based services “To be the place where experiment, theory, and simulation meet and move nanoscience to nanotechnology.” NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 13 Quantum Dots: A Material / Device Testbed Multi-Million Atoms Simulations Designed Optical Transitions Sensors Quantum Dot Arrays Nanoscale Quantum States Atomic Orbitals Structure Computing size: 0.2nm (Artificial Atoms, size 20nm) Problem: Approach: Nanoscale device simulation requirements: •Use local orbital description for individual • Cannot use bulk / jellium descriptions, need atoms in arbitrary crystal / bonding description of the material atom by atom configuration => use pseudo-potential or local orbitals •Use s, p, and d orbitals • Consider finite extent/transport, not infinitely Use GA for material parameter fitting periodic •Strain with VFF => local orbital approach •Custom eigensolver • Need to include > 1 million atoms. •Demonstrated 64 Million Atom System => need massively parallel computers Volume of • The design space is huge: choice of • 110x110x110 nm3 materials, compositions, doping, size, • 15x300x300 nm3 shape. => need a design tool NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 14 Alloy Disorder Problem: Results: • Cations are randomly distributed in alloy • Simulated >1000 dots with random cation dots. distributions. • Does alloy disorder limit electronic • Inhomogeneous broadening factor of structure uniformity for dot ensembles? ~0.5-5meV due to alloy disorder. Approach: Impact: • Simulate a statistical ensemble of alloyed • Fundamental uniformity limit for ensemble dots. of alloy-based quantum dots. • Requires atomistic simulation tool. Simulation of Alloy Dot Ensemble Γ=~0.5-5meV Eeh=1.05eV In0.6Ga0.4As Lense Shaped Dot Diameter=30nm,Height=5nm, GaAs embedded ~1,000,000 Atom Simulation, sp3s* basis Measured Γ=34.6 meV (R. Leon, PRB, 58, R4262) In and Ga atoms are randomly distributed Inhomegenious Broadening? Examined Theoretical Lower Limit NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 15 Computational Nanotechnology NEMO 3-D: Electronic structure for 23 Million Atoms d i r Result / Demonstrations / Impact: g a • 64 million atom strain - r e T 3 volume (110nm) F • 23 million atom electronic structure S N 3 3 Volume (78nm) or 15x178x178nm n o • Determined long range extent of d e strain in self-assembled quantum dots m r o f r e P NCN Morgan State University - Northwestern University - Purdue University - Stanford University - University of Florida - University of Illinois - University of Texas at El Paso 16 NCN Approach to Simulator Development Objective: • Comprehensive nanowire simulator. Approach: • Leverage existing theory, tools and s/w approaches •NEGF theory •NASA, JPL, Purdue, and ASU codes • Utilize post-docs and s/w professionals. X [100] • Deploy the tool to the nanohub. Design Criteria: Status: Separate physics from algorithms! • Development team in place: • Generalized numerical algorithms • 1 S/W architect • General structure descriptions • GUI: 1 s/w professional and 1 post-doc • Si wires • Theory core: 1 post docs • CNTs • Algorithm core: 1 post doc • Ultra-scaled FET • Begun Joining NASA transport code and • Arbitrary materials Purdue transport code • Atomistic and continuum descriptions • prototype on nanoHUB in May. • Graphical User Interface Desired Impact: • Establish community code for community NCN development