Electrical Investigation of Deep-Level Defects Introduced in AlGaN/GaN Heterostructures by CF4 Plasma Treatments

摘要

Al0.24Ga0.76N/GaN heterostructures treated by CF4 plasma at various gas pressures have been electrically investigated using capacitance-voltage and steady-state photo-capacitance spectroscopy techniques. The plasma treatments at gas pressures between 1.3 and 6.7 Pa induced a large positive shift in pinch-off voltage VP from -3.05 V. Additionally, three deep-level defects were newly introduced at similar to 2.1, similar to 2.8, and similar to 3.25 eV below the conduction band. Among them, the similar to 2.1 eV level is considered to be attributable to Ga vacancy-F complexes in the AlGaN layer and to be strongly responsible for the positive shift in VP due to their negatively fixed charges. (C) 2015 The Electrochemical Society. All rights reserved.