Simulation and Characterisation of HfO2/ALGaN/GaN MOS-HEMT with Source Field Plate for Improved Breakdown Voltage

Abstract

The AlGaN/GaN based HEMTs are the most promising devices for high power and high frequency applications, due to wide band- gap material (3.4 eV of GaN), high density of two-dimensional electron gas (2DEG) in the buried channel, low intrinsic carrier density, and high saturation velocity. From this novel device structure by introducing a source field-plated in the metal oxide Semiconductor high electron mobility transistors (MOS-HEMT) structure having a relatively short gate length and short gate-to-drain distances. The 2D break down analysis is performed using Sentaurus TCAD simulator. The effects of gate to drain distance (Lgd),  source field plate length (Lfp) and passivation layer thickness(tp) on break down voltage (BV) is analyzed. The simulations are done using the hydro dynamic (HD) model, which is calibrated / validated with the previously published experimental results. The breakdown voltage is observed to increase with increase in Lf p and tp. Very high breakdown voltage is obtained by optimizing the Lf p to 3 mm and tp to 200nm at a fixed gate to drain distance of 3.4 mm. The results show a great potential application of the ultra-thin HfO2 source field plated AlGaN/GaN MOS HEMT to deliver high currents and power densities in high power microwave Technologies.