High-Temperature Small-Signal Model Analysis Of AlGaN/GaN HEMT

In the exploration of outer space,the output signal of semiconductor detectors for cosmic ray detection is relatively weak and must be used with preamplifier circuit.In recent years,the third generation semiconductor is developing rapidly.Compared with the traditional Si-based devices,GaN-based devices have the characteristics of high and low temperature resistance and radiation resistance,which is suitable for the preamplifier circuit of space particle detectors.In this paper,the small signal equivalent circuit model parameters of AlGaN/GaN high electron mobility transistor(HEMT)devices in space particle detector preamplifier circuit at high temperature are analyzed.This paper reviews the research history of transistor small signal modeling,and analyzes transistor modeling and measurement methods.At present,the research on small signal equivalent model of AlGaN/GaN HEMT transistors is relatively common,but the research on small signal equivalent model of environmental temperature change is very rare.In this paper,AlGaN/GaN HEMT devices with gate length of 34?m and gate width of970?m were fabricated by semiconductor process equipment.A device fixture for measuring the size of the device is designed.The vector network analyzer is used to calibrate the error of the fixture and facilitate the subsequent measurement.The DC characteristics and gate leakage current of the device at high temperature are measured by semiconductor parameter analyzer.The results show that the saturation current of AlGaN/GaN HEMT decreases by about 20%when the temperature increases by 50°C.From the transfer characteristics of the device,it can be seen that the slope of the curve gradually slows down with the increase of temperature,which indicates that the gate control ability of the device decreases with the increase of temperature.At the same time,the temperature has a great influence on the gate leakage current of AlGaN/GaN HEMT device,and the gate leakage current of the device increases sharply with the increase of temperature.Finally,the small-signal equivalent circuit model of AlGaN/GaN HEMT device is analyzed,and the traditional small-signal equivalent circuit model of AlGaN/GaN HEMT is selected.Under the condition of gradually increasing temperature,the parasitic parameters and intrinsic parameters in the model are extracted to analyze the variation law of small signal model parameters.The results show that when the temperature increases,the gate source capacitance C_gs and gate leakage capacitance C_gd decrease with the increase of temperature due to the increase of leakage current in Schottky contact of AlGaN/GaN HEMT devices.The increase of temperature also decreases the mobility of two-dimension electron gas(2DEG),resulting in the increase of resistance R_i and the decrease of conductance G_ds.The decrease of Schottky leakage current and 2DEG mobility will reduce the transconductance g_m of the device with the increase of temperature.