Thermochemistry of Alkylarsine Compounds Used as Arsenic Precursors in Metalorganic Vapor Phase Epitaxy.

Despite their increased safety, alkylarsine compounds have not generally replaced arsine (AsH sub 3) in the metalorganic vapor phase epitaxy (MOVPE) of GaAs because carbon incorporation and high background doping levels. We have studied the thermal decomposition of AsH sub 3 and its alkyl derivatives (methyl, ethyl and butyl compounds), to determine the impact of the thermo-chemistry on growth processes. The thermal stability of the As-precursor compounds was found to decrease in the order AsH sub 3 >Me sub n AsH sub (3-n) >Et sub 3 As>t-BuAsH sub 2. We report the first evidence for production of diarsine (As sub 2 H sub 4) from t-BuAsH sub 2 and for formation of lower substituted methylarsine homologs from Me sub 3 As and Me sub 2 AsH.