Self-limiting etching prior to self-limiting growth in ultra-high vacuum for obtaining clean interface

Intermittent injections of tertiarybutyl-phosphine (TBP) have been applied for molecular self-limiting etching (MSE) of InP substrates in order to obtain clean epilayer/substrate interface prior to growth of InP by molecular layer epitaxy (MLE). The concentrations of impurities, such as C, O, and Si at the interface using MSE decreased compared to those using pre-heating procedure with continuous TBP supply. The MSE mechanism was studied on (111)B oriented InP substrate. It was assumed that C and Si on InP surface and the In atoms on (111)B surface are removed by molecules of TBP or TBP related reactant because of their small binding energies in MSE.