Consideration of discrete interface traps in InGaAs/GaAs heterojunctions

Poisson´s equation has been applied to model the capacitance-voltage (C-V) profile of a Schottky-barrier n-N heterojunction of Au/nIn0.1Ga0.9As/NGaAs. Interface traps, represented either as a box or sheet of charge, have been included in the calculation. Two electron accumulation peaks are observed. One, next to the region depleted of electrons, is related to the interface trap occupancy, and the other is related to the two-dimensional electron gas at the heterojunction. Qualitative agreement is obtained between the calculated and experimentally determined C-V electron profile (300 to 77 K) if a trap EC- 0.13 eV at a concentration -8 × 10¹⁰cm^-2in a 300-Å boxlike distribution is included in the calculation. For MBE grown nIn0.1Ga0.9As/NGaAs deep-level transient spectroscopy suggests that the interface traps are at EC- 0.13 and 0.17 eV with capture cross sections of about 2 × 10^-14and 1 × 10^-15is cm².