The Influence of Technological Parameters of Deposition of Dielectric Layers by the ICP CVD Method on Surface Leakage Currents in AlGaN/GaN HEMT

The influence of technological parameters of deposition of dielectric passivating films by the ICP CVD method (gas ratio, inductively coupled plasma power, substrate temperature, operating pressure) on the structural and electrophysical properties of AlGaN surface layers was studied. It is shown that preliminary plasma-chemical treatment of AlGaN in an oxygen environment leads to the formation of a controlled oxide interface, which reduces surface states and suppresses drain-source leakage currents in the closed state by two to three orders of magnitude. A correlation was established between silicon nitride (SiN) deposition conditions and the degree of plasma-induced damage to AlGaN/GaN heterostructures. To minimize degradation, a composite dielectric based on oxygen-containing silicon nitride (SiON) is proposed. The key result is the development of a combined approach: preliminary modification of the AlGaN surface with oxygen plasma followed by SiON deposition in a low-power ICP CVD regime (power ≤300 W, pressure ≥14 Pa). The obtained results demonstrate the promise of the combined approach (surface pre-modification + controlled passivation) for minimizing the degradation of the electrophysical properties of HEMT structures.