The role of N2 and H2 as carrier gas on the selective area MOVPE of InP-based heterostructures using TBAs and TBP as group-V sources

Hydrogen and nitrogen have been employed as carrier gases for the selective growth of InP-based materials on patterned substrates using tertiarybutyl-arsine (TBAs) and -phosphine (TBP) as alternative group-V sources at different reactor pressures. The properties of the deposited layers have been found to be mainly determined by the diffusion coefficient in the vapour phase, which increases by reducing the reactor pressure or using H2 instead of N2. A higher edge growth, combined with a smaller zone of enhanced growth and, where appropriate, In-enrichment near the masks was detected at atmospheric pressure deposition and for the use of N2, respectively. Furthermore a higher selectivity has been observed for both carriers at reduced reactor pressures and when using H2 instead of N2. Nitrogen as carrier gas offers an additional independent parameter to control the properties of selectively deposited layers and reduces the safety risks of the MOVPE process especially when being combined with less toxic group-V sources.