Introspection Into Reliability Aspects in AlGaN/GaN HEMTs With Gate Geometry Modification

Reliability enhancement of AlGaN / GaN HEMT is a significant thrust area due to rapidly improving material and processing technology. In this paper, a detailed analysis of gate-shaped AlGaN / GaN HEMT with field plate is presented. Although AlGaN / GaN HEMT with field-plate is well known, its blending with gate-shaping leading to a more robust and reliable behaviour is described in this paper. It is observed that the threshold voltage and transconductance invariably remain constant for various combinations of gate-shaped and field plate placements. The threshold voltage for all the devices are found to be - 5.8 V. The peak transconductance for the devices without field plate and with field plate is ~ 0.16 S/mm and ~ 0.15 S/mm, respectively. Apart from leakage current, the electric field also gets mitigated for both gate-shaped and field-plated devices by ~ 45% and ~ 68%, respectively. The moderation in electric field further assists in the reduction of electron temperature for gate-shaped and field-plated structures by ~ 12% and ~ 85%, respectively. Additionally, breakdown voltage increases for the gate-shaped devices to 133 V as compared to 120 V of conventional devices without field plate. Significant reduction in leakage current, electric field, and electron temperature is accompanied by a minor increment in capacitance for the field-plated structure, hence, the proposed structure is expected to enhance reliability of the device. Thus, it is anticipated that the proposed devices with enhanced reliability would be a step ahead of conventional devices and would find major applications in high power domain.