Electrical and structural changes in the near surface of reactively ion etched InP

Near-surface (∼1000 Å) modification in the net carrier concentration in n-type InP (n=6×1015–1.5×1017 cm−3) was observed after reactive ion etching (RIE) in Cl-based (CCl2F2/O2) or organic-based (C2H6/H2) discharges. The carrier loss is slightly more pronounced in the latter case, due possibly to the creation of deep level, compensating acceptors at greater depths as a result of implantation of the light hydrogen ions. Near-complete recovery of the initial carrier density occurs after annealing at 500 °C for 30 s. Structural disorder is detected by ion channeling to depths of ∼400 Å after C2H6/H2 RIE with a self-bias of 380 V. This disorder shows significant recovery after 400 °C, 30 s annealing. Current-voltage measurements on Au Schottky diodes showed ohmic behavior after etching of the InP in a C2H6/H2 discharge, due to the nonstoichiometric surface remaining after RIE. Diodes fabricated on CCl2F2/O2 etched material show only a slight increase in reverse current compared to unetched control samples.