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Temperature and Bias Dependent Trap Capture Cross Section in AlGaN/GaN HEMT on 6-in Silicon With Carbon-Doped Buffer

TitleTemperature and Bias Dependent Trap Capture Cross Section in AlGaN/GaN HEMT on 6-in Silicon With Carbon-Doped Buffer
Publication TypeJournal Article
Year of Publication2017
AuthorsKumar, S, Gupta, P, Guiney, I, Humphreys, CJ, Raghavan, S, Muralidharan, R, Nath, DN
JournalIEEE Transactions on Electron Devices
Volume64
Pagination4868–4874
KeywordsAluminum gallium nitride, Electron traps, HEMTs, logic gates, temperature measurement, wide band gap semiconductors
Abstract

We report on the estimation of trap capture cross section in AlGaN/GaN HEMTs as a function of bias and temperature. Conductance dispersion technique was employed to study the AlGaN/GaN interface of the devices with a carbon-doped GaN buffer grown on 6-in silicon. While a negligible shift in the threshold voltage (VTH) was observed in temperature-dependent IDS-VGS sweeps, we observed a spread in the capacitance-voltage (C-V) measurements, indicating a contribution of interface traps. When biased near depletion, G/ω versus frequency plot for AlGaN/GaN interface exhibits two peaks which correspond to a pair of trap density (Dit) and trap time constant (Tit) values. This was explained using a circuit model in conjunction with energy band diagram. The Dit and Tit values for one peak were in the range from ~ 0.3-7 × 1012/eV · cm2 and 0.6-10 μs while for the other peak, Dit-Tit were in the range of ~0.1-35 × 1012/eV · cm2 and ~0.06-0.3 μs at 25 °C. From the Tit values, electron capture cross section (σ) for both the traps was extracted and was found to be decreasing with increasing temperature in the range of 1.1 × 10-20-1 × 10-19 cm2 and 4.5 × 10-20-1 × 10-17 cm2 for slow traps and fast traps, respectively. A multiphonon emission effect was invoked to explain the temperature dependence of capture cross section.

DOI10.1109/TED.2017.2757516