Wu, P. W.; et al., "The influences of surface treatment and gas annealing conditions on the inversion behaviors of the atomic-layer-deposition Al2O3/nIn0.53Ga0.47As metal-oxide-semiconductor capacitor," Appl. Phys. Lett. 97, 042903 (2010); http:// dx

Normally-off operation AlGaN/GaN high electron mobility transistors have been developed utilising a fluorine-based treatment technique combined with a metal-oxide-semiconductor gate architecture. Threshold voltage as high as 5.1 V was achieved by using an 16 nm-thick Al 2 O 3 gate oxide film. Additionally, the device performed a drain current density of 500 mA/mm and a peak transconductance of 100 mS/mm, which are comparable to the conventional normally-on devices.Introduction: AlGAN/GaN-based high electron mobility transistors are promising candidates for power electronic applications owing to their attractive properties, such as high breakdown field, high electron mobility, and capability of high temperature operation. For power switching applications, devices with normally-off operation are necessary because they can not only help simplify the complexity of the circuit but also reduce standby power consumption. In addition, they provide a fail-safe function because a noise higher than 3 V may occur on the gate electrode during the device operation [1]. Several approaches towards such requirements based on an AlGaN/GaN heterostructure have been investigated, such as the recessed gate [2], fluoride-based treatment [3], and the band diagram engineered approach [4,5]. However, these approaches still encounter an issue which is either lower current density or insufficient threshold voltage for the gate noise blocking. In this Letter, we combined the fluorine-based treatment technique and an Al 2 O 3 film as the gate oxide layer to demonstrate normally-off operation AlGaN/GaN MOS-HEMTs with high threshold voltage, and with comparable current density to conventional normally-on HEMTs

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High-quality epitaxial Ge films were grown on GaAs substrates by ultrahigh vacuum chemical vapor deposition. High crystallinity and smooth surface were observed for these films by x-ray diffraction, transmission electron microscopy, and atomic force microscopy. Direct band gap emission (1550 nm) from this structure was detected by photoluminescence. Valence band offset of 0.16 eV at the Ge/GaAs interface was measured by x-ray photoelectron spectroscopy. N-type arsenic self-doping of 1018/cm−3 in the grown Ge layers was determined using electrochemical capacitance voltage measurement. This structure can be used to fabricate p-channel metal-oxide-semiconductor field-effect transistor for the integration of Ge p-channel device with GaAs n-channel electronic device.