Inverse temperature dependence of reverse gate leakage current in AlGaN/GaN HEMT

Abstract

The experimentally observed inverse temperature dependence of the reverse gate leakage current in AlGaN/GaN HEMT is explained using a virtual gate trap-assisted tunneling model. The virtual gate is formed due to the capture of electrons by surface states in the vicinity of actual gate. The increase and decrease in the length of the virtual gate with temperature due to trap kinetics are used to explain this unusual effect. The simulation results have been validated experimentally.

Admittance spectroscopy and capacitance dispersion of AlGaN/GaN hetero-structures

“…The distribution of these interface trap states in energy space was obtained from equation (4). There is a small energy spread in extracted trap levels from 0.23 eV to 0.25 eV, as evident from the plot in Fig.(4).…”

“…A study of these defects in AlGaN/GaN high electron mobility transistors (HEMTs) is required to utilize their high power capability [1] with good reliability, which still remains a challenge in this technology. The AlGaN/GaN HEMTs suffer from drain current collapse/kink effect [2,3] and high gate leakage currents [4,5]. These problems are attributed by different authors to the traps present in the buffer layer [6], AlGaN barrier [7], and AlGaN surface [4].…”

“…The AlGaN/GaN HEMTs suffer from drain current collapse/kink effect [2,3] and high gate leakage currents [4,5]. These problems are attributed by different authors to the traps present in the buffer layer [6], AlGaN barrier [7], and AlGaN surface [4]. Therefore, a study of the behavior of traps in AlGaN/GaN epitaxial wafers is extremely necessary prior to the fabrication of HEMTs.…”

Current transient spectroscopy for trapping analysis on Au-free AlGaN/GaN Schottky barrier diode

“…1(b), the conduction band will be lifted up due to the trapped electrons (in the AlGaN barrier and in the GaN channel layer) resulting in a lower 2DEG density compared with the fresh condition. 18 This reduction in 2DEG density directly reflects on the increase of the diode on-resistance (in Fig. 1(c)) after constant voltage (V R of À100 V) off-state stress measurement.…”

“…The trapped region at the AlGaN surface in the vicinity of the Schottky contact forms a virtual gate effect and shows a local increase of the surface potential. 18 The modified potential barrier results in a lower tunneling probability and a lower leakage current for the diode. 19 The filling of the traps located in the GaN channel or AlGaN buffer layers (in the access region) will only contribute to the R ON increase rather than affecting the SBH / B directly.…”