Search

The degradation of transient OFF-state leakage current in AlGaN/GaN HEMTs induced by ON-state gate overdrive was observed and studied. The OFF-state leakage current increases significantly with a pre- ON-state gate overdrive. It takes more than 30 s for the leakage current decay to its equilibrium level in dark. The decay processes follow a stretched-exponential law. We propose that this degradation corresponds to the persistent photoconductivity of GaN buffer induced by the electroluminescence during the Schottky gate overdrive. Both the ON-state gate overdrive bias and duration dependences of the OFF-states leakage degradation were studied. This work indicates that gate-protection is necessary to preserve low OFF-state leakage current and improve device reliability. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

AlN/GaN heterostructures with AlN thin film growing by low-thermal-budget (300 °C) plasma-enhanced atomic layer deposition (ALD) were realized on a semi-insulating GaN-on-sapphire template. By applying in situ ALD-grown Al2O3 as the gate dielectric, thin film transistors (TFTs) have been successfully fabricated. The proposed TFTs exhibit effective gate control with a low subthreshold swing of ∼ 85 mV/dec, an ION/ IOFF ratio of 105 and good channel conductive with a low-field mobility of ∼ 27 cm2/(V·s). This mobility is one order of magnitude higher than that achieved in AlN/GaN heterostructures growing by magnetron sputtering. The enhanced device performance is attributed to a high-quality ALD-AlN/GaN interface obtained by in situ remote-plasma pre-deposition cleaning and the single crystal nature of subsequent epitaxial AlN thin film by plasma-enhanced ALD. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]