Correlation of on‐wafer 400 V dynamic behavior and trap characteristics of GaN‐HEMTs

Abstract

A method for identifying the critical traps for the dynamic behavior of gallium nitride high electron mobility transistors (GaN-HEMTs) is described. This method provides information on where the critical traps are located in the horizontal direction. At first, the on-wafer 400 V dynamic behavior of a GaN-HEMT was measured. Acceptor-like trap behavior with 0.14 eV activation energy was observed using conductance analysis. Next, trap characterization was achieved using the capacitance and series conductance transients of a comb-style Schottky barrier diode after electrical stress. Several different biases were applied to determine the locations of the detected traps, because depletion area edges can change upon imposition of different biases. Notably, 0.18 eV acceptor-like trap behavior below the Schottky electrode, 0.44 eV donor-like trap behavior in the access region, and 0.5eV acceptor-like trap behavior in access region were observed. By correlating these diode results with HEMT results, it was concluded that the critical trap behavior likely occurs below the gate electrode in HEMT. As a conclusion, the information obtained with this method should provide useful information for the improvement of device processes.

Gate-Lag in AlGaN/GaN High Electron Mobility Transistors: A Model of Charge Capture

“…9,[15][16][17] In this paper, we suggest both phenomena (i.e. temperature activated capture with no temperature activated current and the appearance of hole traps signals) can be attributed to multistage process involving deep traps in the AlGaN barrier emitting and subsequently capturing electrons, forming a step in the space charge moving toward the AlGaN/GaN interface.…”

“…[12][13][14] In many cases, the current and capacitance relaxations in AlGaN/GaN HEMTs show not only electron-trap-like transitions natural for a majority carrier device such as a HEMT, but also hole-trap-like signals. 9,[15][16][17] In this paper, we suggest both phenomena (i.e. temperature activated capture with no temperature activated current and the appearance of hole traps signals) can be attributed to multistage process involving deep traps in the AlGaN barrier emitting and subsequently capturing electrons, forming a step in the space charge moving toward the AlGaN/GaN interface.…”

Deep traps in GaN-based structures as affecting the performance of GaN devices

“…Such measurements were performed for AlGaN/GaN high-power HEMTs grown on Si (see Refs. [265,269,270]). The traps in the buffer and in the barrier could be separated by applying different steady-state biases and varying the height of the injection pulse.…”

“…The reason for that is the undercutting the 2DEG portion of the channel below the Schottky diode and thus increasing the effects of series resistance. In that sense multifinger rectangular Schottky diodes with narrow fingers are preferable (see [265,267,269,270]). …”

“…The temperature dependence of capacitance and conductance recovery time transients upon application of various gate voltages was measured for wide comb-like Schottky diodes and compared to the drain current relaxation times of 400 V AlGaN/GaN HEMT on SiC [270]. The transistor characteristics were analyzed using the relaxation times spectra characterization method of Ref.…”