Post-annealing effects on device performance of AlGaN/GaN HFETs

The impact of post gate annealing on microwave noise performance of AlGaN/GaN HEMTs

“…Devices on sapphire substrate were first annealed under different conditions for process optimization. After comparing performance of devices on sapphire substrate before and after annealing, 400°C for 10 min annealing was used in this study, which gave the best trade-off among drain saturation current, transconductance, and breakdown voltage [10]. Devices on SiC substrate were annealed under this condition and the DC, small signal, and noise performances were measured before and after annealing.…”

“…Recently, during the investigation of thermal stability of Schottky contacts on AlGaN/GaN heterostructures, we demonstrated that post gate annealing under certain conditions could increase the Schottky barrier height and reduce the reverse leakage current of Ni Schottky diodes for more than three orders of magnitude [9]. For HEMT devices, we demonstrated that post Schottky gate annealing technique could improve the device breakdown voltage, unit currentgain frequency (f T ), maximum power frequency (f max ) and output power [10]. In this paper, we report the effect of post gate annealing technique on the microwave noise performances of AlGaN/GaN HEMTs.…”

Temperature‐dependent microwave noise performances of AlGaN/GaN HEMTs with post‐gate annealing

“…T-shape gates were patterned by electron beam lithography with a length of 0.2 µm and Ni/Au was used as the Schottky contact metal. After the gate metallization, the devices were annealed in a furnace in N 2 ambient at 400°C for 10 minutes, which gave the best trade-off among drain saturation current, transconductance, and breakdown voltage [13].…”

“…Recently, in the process of investigation of the thermal stability of Schottky contacts on AlGaN/GaN heterostructures, we demonstrated that post-Schottky-metallization annealing in furnace under certain conditions can increase the Schottky barrier height and reduce the reverse leakage current of Ni Schottky diodes for more than three orders of magnitude [12]. When the same technique was applied to AlGaN/GaN HEMTs, we demonstrated that by using the optimized conditions, the device breakdown voltage, the cut-off frequency (f T ), the maximum oscillation frequency (f max ), and output power can be greatly improved after the post-gate-annealing (PGA) [13]. In this paper, we present the temperature dependant microwave noise performance of AlGaN/GaN HEMTs with and without PGA process.…”

A low‐leakage and reduced current collapse AlGaN/GaN heterojunction field effect transistor with AlOx gate insulator formed by metal‐organic chemical vapor deposition

“…However, before HFETs can begin to be used widely in the electronics market, the large gate leakage inherent in current HFET implementations must be improved. Various approaches to this problem have been attempted, including the design of alternative device structures [3], the adoption of new process designs [4], and pursuing optimizations in epitaxial growth condition [5]. The use of a metalinsulator-semiconductor (MIS) structure [3] directly blocks the leakage current by inserting a highly insulating material at the Schottky interface [3].…”