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

Abstract

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.INDEX TERMS Capacitance voltage (CV), electron temperature, GaN HEMT, gate shape, leakage current.

Novel Stacked Passivation Structure for AlGaN/GaN HEMTs on Silicon With High Johnson’s Figures of Merit

“…The higher dielectric constant leads to higher gate capacitance (CG) [22] . The dependency between CG and VGS is studied by performing AC analysis with frequency of operation fixed at 1 MHz [23] , source and drain terminals being grounded, and VGS being swept from -6 V to 0 V. In sample C, the HfO2 with a length of 500 nm on the gate side near the drain mostly increases CGD. As shown in Fig.…”

Investigation of Electric Field Profile and associated parameters with Embedded Metal Layer in Field Plate AlGaN/GaN HEMTs

“…This adversely affects the device's performance, lifetime, and reliability, limiting the operational capability. Prior work has demonstrated the use of high-k dielectric passivation layer [8,9], field plates (FP) [10,11,12,13,14], and modified gate geometry [15,16,17] to moderate the electric field at the drain side of the gate edge of the device thereby enhancing the breakdown voltage. Zhang et al [18] demonstrated a recessed float field plate in millimeter-wave AlGaN/GaN HEMTs that modulates the electric field distribution at the drain end of the gate edge, thereby increasing the breakdown voltage.…”