Modeling of HVPE of GaN, AlN and AlxGa1-xN with Virtual Reactor

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  • 1. Software for Modeling of Long-Term Growth of GaN, AlN and AlxGa1-xN Bulk Crystals and Epilayers by Hydride Vapor Phase Epitaxy HEpiGaNS™ Virtual Reactor edition for HVPE STR-Group Ltd www.str-soft.com 2009 Copyright © 2009 STR Group Ltd. All rights reserved
  • 2. HEpiGaNs Physical Model Global Heat Transfer Heat transfer by conduction, convection, and radiation Anisotropy Radio Frequency and Resistive Heating Species Transport Convection Multi-component diffusion Advanced models of heterogeneous process Prediction of the growth rate profile and distribution of V/III ratio over the substrate Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 3. HEpiGaNs Heat Transfer and Flow in the Reactor GaN deposition on the substrate Parasitic GaN deposition Gaseous species: NH3, GaCl, HCl, H2 Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 4. HEpiGaNs Heat Transfer and Flow in the Reactor Flow pattern in the vicinity of the substrate Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 5. HEpiGaNs GaN Configuration: Mass Transport Modeling Species Mass Fraction Distributions Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 6. HEpiGaNs GaN Configuration: Mass Transport Modeling Species Mass Fraction Distributions Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 7. HEpiGaNs GaN Configuration: Mass Transport Modeling 120 Growth rate and V/III ratio profiles along 100 the substrate radius V gr , µm/h 80 60 40 2000 20 V / III ratio 1500 0 0.02 0.03 0.04 0.05 0.06 r, m 1000 500 0.02 0.03 0.04 0.05 0.06 Substrate r, m Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 8. HEpiGaNs Ga Source Modeling GaCl generation due to liquid Ga evaporation Liquid Ga evaporation HCl supply HCl consumption on the surface of liquid Ga Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 9. HEpiGaNs AlGaN Configuration: Basic Assumptions Gaseous species: AlCl3, GaCl, AlCl, GaCl3, NH3, H2, HCl, N2 Supply of precursors: • AlClx and GaClx on the inlet • HCl on the inlet, boats with liquid Ga and solid Al inside the reactor Reactions on AlxGa1-xN surface: • AlCl3 (gas) + NH3 (gas) = AlN (solid) + 3HCl (gas) • AlCl (gas) + NH3 (gas) = AlN (solid) + HCl (gas) + H2 (gas) • GaCl (gas) + NH3 (gas) = GaN (solid) + HCl (gas) + H2 (gas) • GaCl3 (gas) + NH3 (gas) = GaN (solid) + 3HCl (gas) Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 10. HEpiGaNs AlGaN Configuration: Basic Assumptions Reactions on Al source: • 2Al (solid) + 2HCl (gas) = 2AlCl (gas) + H2 (gas) • AlCl (gas) + 2HCl (gas) = AlCl3 (solid) + H2 (gas) Reactions on Ga source: • 2Ga (liquid) + 2HCl (gas) = 2GaCl (gas) + H2 (gas) • GaCl (gas) + 2HCl (gas) = GaCl3 (solid) + H2 (gas) Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 11. HEpiGaNs AlGaN Configuration: Mass Transport Ga, 850 oC HCl + N2/H2 Growth conditions - HCl flow rates through Al and Ga NH3 + GaCl sources are varied to specify the Al N2/H2 HCl + N2/H2 content in AlxGa1-xN Al, 550 oC AlCl3 - Carrier gas is either pure N2 or 90%N2 + 10%H2 Sapphire substrate, 1100 oC Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 12. HEpiGaNs AlGaN Configuration: Mass Transport Species Distribution in the Growth Chamber AlCl3 AlCl Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 13. HEpiGaNs AlGaN Configuration: Mass Transport Species Distribution in the Growth Chamber GaCl GaCl Carrier is pure N2 Carrier is 90%N2 + 10%H2 Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 14. HEpiGaNs Al Content in the Growing AlxGa1-xN layer 1 0.9 - Incorporation of Ga in AlGaN is sharply 0.8 hampered by carrier H2 due to slowing down the growth reaction 0.7 GaCl + NH3 -> GaN(s) + HCl + H2 0.6 x_Al 0.5 - Incorporation of Al in AlGaN is not 0.4 hampered by carrier H2 as it is not 0.3 Modeling, H 2 = 0 % involved in the growth reaction 0.2 Modeling, H 2 = 1 % AlCl3 + NH3 -> AlN(s) + 3HCl Modeling, H 2 = 10 % 0.1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 R_Al Al content in the growing AlGaN layer (x_Al) as a function of Al content in the vapor (R_Al) at various concentration of H2 in carrier Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 15. HEpiGaNs Al Content in the Growing AlxGa1-xN layer 1 1 0.98 0.9 H 2 = 10 % 0.96 0.8 x_Al x_Al 0.94 0.7 0.92 0.6 H 2 = 10 % 0.9 0.5 0 100 200 300 400 500 0 10000 20000 30000 40000 50000 Q(AlCl3) + Q(GaCl) Q(NH 3) Al content vs. group-III Al content vs. NH3 Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 16. HEpiGaNs AlN Configuration: Validation 150 150 Comp., average Comp., average Comp., axis Comp., axis Exp. Exp. Growth Rate, µm/h Growth Rate, µm/h 100 100 50 50 Q(N2) = 100 sccm Q(N2) = 200 sccm Q(H 2) = 100 sccm Q(H 2) = 0 sccm 0 0 0 1 2 3 4 0 1 2 3 4 Q(NH 3), sccm Q(NH 3), sccm Growth in Pure N2 Growth in N2 + H2 B. Armas et al., Surf. Coat.Tec. 123 (2003) 199 Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 17. HEpiGaNs AlN Configuration: Validation 300 Comp., average 250 Comp., axis Exp. Growth Rate, µm/h 200 150 100 Q(N2) = 100 sccm 50 Q(H 2) = 100 sccm 0 0 1 2 3 4 Q(AlCl3), sccm Growth in N2 + H2 B. Armas et al., Surf. Coat.Tec. 123 (2003) 199 Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 18. HEpiGaNs AlGaN Configuration: Validation - Incorporation of Ga in AlGaN is sharply hampered by carrier H2 due to slowing down the growth reaction GaCl + NH3 -> GaN(s) + HCl + H2 - Incorporation of Al in AlGaN is not hampered by carrier H2 as it is not involved in the growth reaction AlCl3 + NH3 -> AlN(s) + 3HCl A. Koukitu et al, JCG 305 (2007) 335 Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 19. HEpiGaNs Computational Mesh: 0.2 Quadrilateral (in Long Tubes) and Triangular (in the Growth Zone) 0.18 0.16 Long rectangular tubes: quadrilateral mesh with high (~10-20) aspect ratio Height, m 0.14 Growth domain with complex shape and with moving crystal and deposit 0.12 interfaces: triangular mesh 0.1 0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 Radius, m Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 20. HEpiGaNS™ Evolution of Semi-Bulk GaN Crystal and GaN Polycrystalline Deposits in Long-Term Growth Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 21. HEpiGaNs Schematic View of the Reactor GaN deposition on the substrate Parasitic GaN deposition Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 22. HEpiGaNs Crystal Shape Evolution Start of the growth Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 23. HEpiGaNs Crystal Shape Evolution t=5h Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 24. HEpiGaNs Crystal Shape Evolution t = 10 h Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 25. HEpiGaNs Thermal Stress Evolution in the Growing Crystal t=0 t=5h t = 10 h Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com
  • 26. Conclusions HEpiGaNS™ is an effective tool for simulation of long-term bulk growth and epitaxy of GaN, AlN and AlxGa1-xN by HVPE Any questions regarding HEpiGaNS™ software tool can be sent via http://www.str-soft.com/contact/ General presentation demonstrating capabilities of the Virtual Reactor software package and presentations demonstrating other editions of Virtual Reactor family, such as • VR-PVT SiC™ • VR-PVT AlN™ • VR-CVD SiC™ are available upon request Copyright © 2009 STR Group Ltd. All rights reserved www.str-soft.com