Layer-by-Layer Growth of GaN on GaAs Substrates by Alternate Supply of GaCl3 and NH3

Atomic layer epitaxy (ALE) of GaN on GaAs substrates was tried by alternate supply of GaCl3 and NH3, and the growth process was analyzed by the surface photo-absorption (SPA) method. When the GaN layers were grown on GaAs surface at 500° C, typical SPA signals indicating the layer-by-layer growths were observed. Change in the reflection intensity (SPA signal) after the GaCl3 supply for the GaN growth was much slower than that of GaAs. This result indicates that the reaction between GaCl3 and N or NH3 was much slower than that between GaCl3 and As or AsH3. The crystallinity of GaN grown on (001) GaAs was almost amorphous. On the other hand, the GaN grown on (111) GaAs had a wurtzite structure and was a single crystal.