Analysis of AlGaN/GaN HEMT and Its Operational Improvement Using a Grated Gate Field Plate

This paper investigates the DC and RF performance of a gate field plate (GFP) and proposed grated gate field plate (GGFP) AlGaN/GaN high electron mobility transistor (HEMT) with a gate length of 0.25 mu m through experimentally calibrated simulations. The GFP HEMT technology enhances breakdown voltage but influences the capacitive nature of the device with parasitic capacitance, particularly Miller's capacitance, into action reducing its radio frequency and switching performance. To improve the electrical operation of a GFP HEMT, a grated gate field plate (GGFP) HEMT structure is proposed which exhibits operational improvements in terms of output current (1 A/mm), transconductance (350 mS/mm), and at the same time, reduces the parasitic capacitance effectively. We observe a 60% improvement in cut off frequency of the proposed GGFP HEMT (28.3 GHz) with respect to GFP HEMT (17.6 GHz) with little decrease in breakdown voltage. This study shows that the proposed device structure (GGFP HEMT) due to its effective capacitance reduction has better suitability and is a viable technique for future radio frequency applications.