Trapping Effects on Leakage and Current Collapse in AlGaN/GaN HEMTs
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https://doi.org/10.1007/s11664-020-08299-0 Ó 2020 The Minerals, Metals & Materials Society
Trapping Effects on Leakage and Current Collapse in AlGaN/ GaN HEMTs NIKETA SHARMA ,2,4 C. PERIASAMY,2 NITIN CHATURVEDI,3 and NIDHI CHATURVEDI1 1.—Smart Sensor Area, CSIR-Central Electronics Engineering Research Institute, Pilani 333031, India. 2.—Department of Electronics and Communication Engineering, Malaviya National Institute of Technology, Jaipur 302017, India. 3.—Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science, Pilani 333031, India. 4.—e-mail: [email protected]
In this paper, we showcase our investigation regarding the effect of acceptor traps in GaN buffer and AlGaN barrier layers on the leakage current and current collapse in GaN high-electron-mobility transistors. The dependence of current collapse and leakage current on the density and energy level of traps is carefully considered. With an increase in trapping density from 1015 cm3 to 1018 cm3, the leakage current was significantly reduced from 80.2% to 1.76% in the buffer layer and 95% to 12.6% in the barrier layer, while the current collapse increased from 6% to 89.8% in the buffer layer and 0.3% to 17.5% in the barrier layer. The effects of current collapse and leakage were more noticeable in the buffer layer than in the barrier layer. Different energy levels (0.75 eV, 1.8 eV, and 2.85 eV) of acceptor traps were likewise studied. It was demonstrated that high-energy traps induced a lower amount of leakage, while the current collapse was greater. Based on these results, a balanced trade-off between the current collapse and the leakage current is proposed. Key words: Current collapse, drain current, GaN HEMTs, traps, transconductance
INTRODUCTION In recent years, gallium nitride (GaN)-based high-electron-mobility transistors (HEMTs) have garnered much interest for use in high-power, high-temperature, high-frequency, and biosensing applications due to their exceptional combination of fundamental properties including high electron sheet carrier concentration, high energy bandgap, high thermal conductivity, and high electron mobility.1–6 However, the performance of these devices can be constrained by the presence of structural imperfections, dislocations, and trap-related phenomena in HEMT structures.7–10 Trapping effectrelated issues such as current collapse, high leakage current through the buffer layer, and reduced
(Received November 16, 2019; accepted June 25, 2020)
breakdown voltage need to be addressed to improve the long-term reliability of the HEMT structures.11–14 These traps/deformity levels can be generated during material growth or device processing and introduce deep-level acceptors. The acceptor-type traps in the GaN buffer and AlGaN barrier layers are necessary for the device to function, but the appropriate combination of trap density and energy level can suppress leakage current. Herein, it is shown that the density of an acceptor-type trap in the buffer/barrier layer and the trapping energy l
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