Study of the effect of the gate’s length on the electrical quality of AlGaN/GaN heterostructures based HEMTs

This study examines the influence of gate length variation on the electrical properties of AlGaN/GaN High Electron Mobility Transistors (HEMTs), with a focus on Schottky gate characteristics. Devices with gate lengths of 1 µm, 20 µm, 30 µm, and 100 µm were analyzed using I-V measurements to extract key electrical parameters, including series resistance, ideality factor, Schottky barrier height, and leakage current. The results reveal that shorter gate lengths, particularly 1 µm, exhibit a high ideality factor (n = 7.51) and substantial series resistance (Rs ≈ 1.15×109 Ω), indicating dominant trap-assisted tunneling and recombination effects. In contrast, the 100 µm device demonstrates superior performance, with a lower ideality factor (n = 1.12) and reduced leakage current. The Schottky barrier height varies from 0.640 eV (30 µm) to 0.743 eV (100 µm), while leakage current increases significantly in shorter gate devices, reaching 5.50×10⁻¹⁰ A at 1 µm. These findings highlight the crucial role of gate length optimization in improving the performance of GaN-based HEMTs for high-frequency and high-power applications, contributing to the development of next-generation GaN transistors with enhanced efficiency and reliability.