Invited paper. Anodic oxides on GaAs. IV. Thin anodic oxides on GaAs

Abstract

As the anodic oxides produced on GaAs become thinner, the highly resistive nature of the oxides changes rapidly, allowing large leakage or tunnelling currents through the oxide without, however, permanently changing the original properties of the oxide layer. A considerable deviation from ideal insulator properties was observed with native oxides thinner than about 250 A, and with anodic AI2O3. thinner than 100 A. In the reverse bias conditions, MOS structures employing very thin oxides (< 100 A) can allow leakage currents of a few A cm-2 with non-destructive white light emission. By limiting the minority carrier leakage currents, inversion changes can be made to accumulate near the GaAs surface and with such thin oxide GaAs MOS structures, light-enhanced currents were observed with large enhancement factors.