Abstract
Deposition of single crystalline gallium nitride (GaN) was done using atomic layer epitaxy (ALE) technique with trimethylgallium (TMG) and ammonia (NH3) as the reactants, at temperatures, T, ranging from 753 to 963 K. The process variables to obtain self-limiting growth mode were investigated. For T = 853 K, ALE growth of GaN was accomplished by alternative pulsing 0.072 mol% of TMG for 4 seconds and 98.3 mol% of NH3 for 6 seconds. Kinetic analysis of the growth rates per ALE cycle as a function of exposure time for each reactant was performed. The results showed that activation energy for each half reaction increased with increasing surface coverage. An averaged activation energy of 26.3 kcal/mol was obtained for the reaction of NH3 on Ga-terminated surfaces, 27.7 kcal/mol for TMG on N-terminated surfaces. The large concentration supply ratio of [NH3]/[TMG] (about 1400) that makes NH3 adsorb as much as TMG may be responsible for the comparable activation energies.
