Current Voltage and Transconductance 2-D Model for Dual Material Gate AlmGa1-mN/GaN Modulation Doped Field Effect Transistor for High Frequency Microwave Circuit Applications

In this paper we present current voltage and trans-conductance model for Dual Material Gate AlGaN/GaN HEMT. Our proposed model demonstrates complete charge control in 2DEG based channel of the device in order to investigate the current-voltage as well as transfer characteristics of the device under various gate and drain biases. The proposed device structure uses GaN material capable to withstand higher breakdown voltage with polarization induced charge carrier density to achieve higher channel current density at higher operating voltages [24]. Our model and TCAD simulation results reveal that DMG AlGaN/GaN HEMT structure is capable of minimizing short-channel effects (SCEs) in a better way as compared to the available conventional devices due to the presence of the step in the channel potential distribution which is capable to screen the drain potential variation in the device operation. Our model accurately derives the currents by using accurate device threshold model based on analysis of two dimensional electron gas in the channel. It is found that work function difference of dual metal engineered gate design is reason behind the screening effect of the drain potential variation near the drain region resulting in suppressed drain induced barrier lowering (DIBL). The model effectively analyses current density in the device channels which is based on spontaneous and piezoelectric polarization induced 2-DEG density. High trans-conductance 162 mS/mm of our device model is attributed to improved charge control by dual material engineered gate structure design which further result in better electron transport properties in device channel . A good agreement between the results obtained from the model, ATLAS device simulator and published experimental data provides the validity and correctness of the proposed model.