Effects of annealing, using a plasma-excited chemical vapor deposition SiN film as a cap, on the carrier density of AlGaAs/GaAs heterostructures and Si-doped GaAs

Abstract

We investigate how the mobility and carrier density of AlGaAs/GaAs two-dimensional electron gas are influenced by the fabrication process with plasma-excited chemical vapor deposition (plasma-CVD) SiN film. These properties are greatly reduced by annealing with plasma-CVD SiN film as a cap but are restored by reannealing after removing the SiN film. We further use capacitance-voltage measurements to investigate the influence of this same process on a more simplified structure, Si-doped GaAs layer. Annealing with a plasma-CVD SiN film changes the defect density of Si-doped GaAs in two, temperature dependent ways: annealing below 380 °C reduces deposition damage, and annealing above 300 °C produces new defects, which might be caused by the film stress. These new defects can be reduced by reannealing after removing the SiN film.