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The authors are reporting for the first time the fabrication of GaN‐based fully‐vertical high‐power metal‐oxide‐semiconductor field effect transistors on Si. The electrical measurements of the fabricated device exhibited both vertical and lateral modes of operation. The transfer characteristics of the device in vertical mode showed a peak trans‐conductance (Gm,max) of 23.6 mS/mm with a threshold voltage (Vth) of −19.6 V. The maximum current drain density (ID,max) of 249.3 mA/mm was observed with ON‐resistance (RON) of 44.2 Ω‐mm. The electrical results obtained in the vertical mode were also compared with the laterally oriented devices. The comparison of the electrical results indicates a relatively higher ON‐resistance of the device in the vertical configuration, due to the contribution of the series resistance of the buffer layers in the epi‐structure. [ABSTRACT FROM AUTHOR]

The surface passivation for InGaN/GaN multilayer solar cells was investigated, and it was confirmed that the device with an atomic‐layer‐deposited (ALD) Al2O3 passivation film showed high internal and external quantum efficiencies of 99 and 84%, respectively, along with a high energy conversion efficiency of 1.31% under a 1‐sun air‐mass 1.5 global illumination. The current−voltage characteristics indicated that the ALD Al2O3 film improved the surface electrical stability. The carrier lifetime measurements revealed that the ALD Al2O3 film reduced the surface carrier recombination rate and thereby contributed to the improvement of the solar cell performance in a short wavelength region. [ABSTRACT FROM AUTHOR]

A high current gain cutoff frequency (fT) of 90 GHz and a peak maximum oscillation frequency (fMAX) as high as 150 GHz are reported for a rectangular‐shaped gate AlGaN/GaN high‐electron mobility transistor (HEMT) on a high resistive silicon (HR‐Si) substrate. The combined high fT/fMAX values for 100 nm unpassivated gate device demonstrate the high‐quality heterostructure on silicon substrate. The reported high‐performance RF device characteristics are comparable and even superior to the existing passivated AlGaN/GaN HEMTs of similar gate length. In addition, good DC characteristics have been recorded with the drain current density and an extrinsic transconductance of 0.6 A/mm and 157 mS/mm, respectively. [ABSTRACT FROM AUTHOR]

An application for a transparent gate electrode with surface‐side electroluminescence (EL) observation is proposed for identification of the gate leakage path in AlGaN/GaN high electron mobility transistors. This technique enables surface‐side EL observation throughout the gate electrode, so that the substrate material is unrestricted. Through the transparent gate, a non‐uniformly located spot‐shape EL was clearly observed. By comparing devices with different leakage currents using EL intensity, the location marked by the spot‐shape EL is found and demonstrates a dominant leakage path. [ABSTRACT FROM AUTHOR]

The realisation of a fully vertical gallium nitride (GaN)-on-silicon (Si) Schottky barrier diode (SBD) without using wafer bonding and Si substrate removal process is reported. The SBD presented a turn-on voltage of 0.69 V at 1 A/cm², breakdown voltage of 148 V with a specific on-resistance of 13.9 mO cm². The ideality factor and Schottky barrier height were 1.35 and 0.71 eV, respectively. An effective critical electric field was estimated to be 1.48 MV/cm. The Baliga's figure of merit for the SBD was calculated to be 1.57 MW/cm². These results indicate the great potential of GaNon- Si in achieving cost-effective fully vertical power device. [ABSTRACT FROM AUTHOR]