3. Compare of epitaxial methods Some of the sources like AsH 3 are very toxic. Use metalorganic compounds as the sources 1968 MOCVD (Metal-Organic Chemical Vapor Deposition) Hard to grow materials with high vapor pressure Deposit epilayer at ultrahigh vacuum 1958 1967 MBE (Molecular Beam Epitaxy) No Al contained compound, thick layer Use metal halide as transport agents to grow 1958 VPE (Vapor phase epitaxy Limited substrate areas and poor control over the growth of very thin layers Growth form supersaturated solution onto substrate 1963 LPE (Liquid phase epitaxy) limit features time Growth method

4. Some about the name of MOCVD In the reference, MOCVD also have some other names. Different people prefer different name. All the names refer to the same growth method. MOCVD (Metalorganic chemical vapor deposition) OMCVD(Organometallic CVD) MOVPE (MO vapor phase epitaxy) OMVPE AP-MOCVD (Atmosphere MOCVD) LP-MOCVD (Low pressure MOCVD)

5. 2. The MOVD growth system

6. MOCVD Growth System Vacuum and Exhaust system Gas handle system Computer Control Reactor

8. Reactor-1

9. Reactor-2

10. Aixtron Model-2400 reactor

13. Vapor pressure of most common MO compounds Log[p(torr)]=B-A/T Cp2Mg DEZn TEIn TMIn TEGa TMGa TEAl TMAl 175 10.56 3556 0.05 Mg(C 5 H 5 ) 2 -28 8.28 2190 8.53 Zn(C 2 H 5 ) 2 -32 8.94 2815 0.31 In(C 2 H 5 ) 3 88 9.74 2830 1.75 In(CH3) 3 -82.5 9.19 2530 4.79 Ga(C 2 H 5 ) 3 -15.8 8.50 1825 238 Ga(CH 3 ) 3 -52.5 10.78 3625 0.041 Al(C 2 H 5 ) 3 15 10.48 2780 14.2 (Al(CH 3 ) 3 ) 2 Melt point ( o C) B A P at 298 K (torr) Compound

16. reaction

18. 6. MOCVD grow GaN and related materials Two Step MOCVD Growth procedure Ga(CH 3 ) 3 +NH 3 GaN+CH 4 High temperature treatment Buffer layer Epilayer Growth TMGa NH 3 Temperature 1150 o C 550 o C 1050 o C