The effect of group V precursor on selective area MOVPE of InP/GaAs-related materials

Abstract

Tertiarybutylphosphine (TBP) and tertiarybutylarsine (TBAs) are widely used as alternative group V precursors for phosphine and arsine, mainly because of their comparatively low toxicity and low decomposition temperature. In this work, the effect of group V precursors on selective area metal-organic vapor phase epitaxy (MOVPE) of InP/GaAs-related materials was studied, in terms of the surface sticking probabilities of group III intermediates. The sticking probabilities were measured by analyzing the thickness profiles of selectively grown films of GaAs and InP in 380-μm-wide growth area between SiO 2 masks. The sticking probability of the In precursor was about 3.2 times larger in the growth with PH 3 than with TBP at 823 K. The sticking probability of the Ga precursor was nearly the same whether the group V source was AsH 3 or TBAs. Such differences were manifested in the In/Ga ratio of selectively grown In x Ga 1− x P. The difference in the sticking probabilities between the precursors of In and Ga mainly determined the In/Ga ratio. Based on a linear combination model using measured values of sticking probabilities, the variation of the composition was predicted to be larger in the growth with phosphine than with TBP. Measurement of the In/Ga composition using electron-probe micro analysis confirmed that prediction. It was proved that the kind of group V precursor is an important factor that governs composition uniformity in selective area MOVPE.