Electrothermal Modeling and Analysis of GaAs-Based Nano HEMT
摘要
This research investigates the effect of temperature variation on the performance characteristics of an AlGaAs/GaAs nano-scale High Electron Mobility Transistor (HEMT). Temperature measurements have been performed on the wafer, spanning a range of −40 °C to 150 °C. Important parameters were examined, including swing, subthreshold slope, threshold voltage (VT), gate leakage currents (GLC), ON and OFF currents, and the ION/IOFF ratio. Strong quantum confinement at the AlGaAs/GaAs heterointerface (~ 33 nm), where a distinct two-dimensional electron gas (2-DEG) forms, is confirmed by the conduction band analysis. Sub-band energy levels represent quantized energy states necessary for high-speed operation, with the first sub-band (ψ₁) at roughly 0.11 eV. The on-state Schottky gate leakage current (GLC) increases from − 1.43 × 10⁻⁹ A to −6.17 × 10⁻⁷ A, indicating enhanced thermionic emission and trap-assisted tunneling mechanisms, while the off-state GLC increases from 2.2 × 10⁻⁹ A to 6.02 × 10⁻⁷ A. Temperature also affects electrostatic performance: the threshold voltage (VT) changes from − 0.50 V at −40 °C to −0.60 V at 150 °C, and the saturation drain current (Idss) at Vgs = 0.8 V decreases from 37.6 mA to 31.85 mA. Notwithstanding these deteriorations, the device has a Zero Temperature Coefficient (ZTC) point at Vgs = −0.75 V, where on-resistance and drain current are both stable. This is very beneficial for analog and radio frequency applications. Furthermore, despite decreasing from 3.71 × 10⁵ at −40 °C to 9.10 × 10⁴ at 150 °C, the ION/IOFF ratio—a crucial indicator for digital switching—remains acceptable. The subthreshold swing and slope values exhibit slight fluctuation, suggesting that switching characteristics are maintained. The device retained strong switching capability and advantageous electrostatic properties, making it appropriate for high-temperature and power applications even though performance declined at higher temperatures.