Reflectance anisotropy studies of the growth of InP on InP(001) at atmospheric pressures using tertiarybutylphosphine and trimethylindium

There is currently much interest in developing precursors for the vapour phase growth of compound semiconductors as alternatives to the hazardous group V hydride precursors arsine and phosphine. For InP growth in particular, the precursor tertiarybutyl phosphine (TBP) is known to perform well in terms of the quality of the resulting epilayers but little is known regarding the gas-phase or surface-phase chemistry of this compound. In order to study the surface chemistry under typical growth conditions, we have investigated the nature of the surface reactions that occur at atmospheric pressures when growing InP on InP(001) substrates from TBP and trimethylindium (TMIn) using the novel "epioptic" technique known as reflectance anisotropy (RA). Here we report the findings of experiments in which the interaction of TMIn (specifically) and TBP (indirectly) with the substrate surface were monitored at temperatures in excess of 300°C as they were introduced into a conventional growth reactor in a sequential manner, during an atomic layer epitaxy growth cycle. These experiments demonstrate clearly that the RA technique is a particularly powerful in-situ probe of growth kinetics.