Defects in as-processed, irradiated, and stressed GaAs-based device structures

GaAs and its semiconductor alloys are of increasing interest for use in highly-scaled, high-frequency CMOS and 3-D ICs. In devices with insulating layers, charge trapping by defects in the gate oxide often dominates the device’s radiation response. In devices without these insulating layers, process maturity has generally decreased the impact of many well-understood defects leading to the emergence of a wider range of defects and impurities limiting device performance and reliability. In this work, we begin with a re-evaluation of the origin of observed significant increases in thermal generation rates for p-i-n-i-p GaAs structures attributed to depassivation of hydrogen-defect/impurity complexes during electron-beam irradiation. Density-functional-theory (DFT) calculations of defect energy levels and reaction pathways suggest depassivation of O_As-H complexes as a likely explanation. Turning to more contemporary GaAs/AlGaAs-based pseudomorphic high-electron mobility transistors, 1/f noise spectra show three prominent peaks associated with defect activation energies. Through a combination of DFT calculations and literature review, we discuss plausible origins of these peaks, including oxygen-based defects, DX centers, and other impurities.