PYROLYSIS OF ORGANO-AS PRECURSORS STUDIED BY SURFACE PHOTOABSORPTION

Surface Photo-Absorption (SPA) is an in situ optical technique for monitoring growth processes. It can measure the dynamics of surface reaction on a growth surface. We use SPA to investigate the pyrolysis of As precursors such as organo-arsenic and arsine (AsH3), and estimate the decomposition activation energies of these As precursors. The results indicate that tertiary butylarsine (tBAs), diethylarsine (DEAsH) and AsH3 which all contain a hydrogen-As bond, have lower activation energies than might be expected from the average bond strength, indicating that their pyrolysis processes are well catalyzed by the GaAs surface. On ther other hand, trialkylarsine such as trimethylarsine (TMAs) and triethylarsine (TEAs) have high activation energies. As expected from the low activation energy, high-quality GaAs can be grown using tBAs.