Crack-free AlGaN/GaN high-electron-mobility transistors (HEMTs) grown on a 200 mm Si substrate by metal–organic chemical vapor deposition (MOCVD) is presented. As grown epitaxial layers show good surface uniformity throughout the wafer. The AlGaN/GaN HEMT with the gate length of 1.5 µm exhibits a high drain current density of 856 mA/mm and a transconductance of 153 mS/mm. The 3.8-µm-thick device demonstrates a high breakdown voltage of 1.1 kV and a low specific on-resistance of 2.3 mΩ cm2 for the gate–drain spacing of 20 µm. The figure of merit of our device is calculated as 5.3×108 V2 Ω-1 cm-2.

We report recessed-gate Al2O3/AlGaN/GaN normally-OFF metal–oxide–semiconductor high-electron-mobility transistors (MOS-HEMTs) on 8 in. Si. The MOS-HEMTs showed a maximum drain current of 300 mA/mm with a high threshold voltage of +2.4 V. The quite low subthreshold leakage current (∼10−8 mA/mm) yielded an excellent ON/OFF current ratio (9 × 108) with a small, stable subthreshold slope of 74 mV/dec. An atomic-layer-deposited Al2O3 layer effectively passivates, as no significant drain current dispersions were observed. A high OFF-state breakdown voltage of 825 V was achieved for a device with a gate-to-drain distance of 20 µm at a gate bias of 0 V.

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Hydride vapor phase epitaxy (HVPE), which enables low-cost crystal growth, has garnered attention as an alternative III-V device fabrication technology to metal organic chemical vapor deposition. However, improvement in solar cell performance, through the introduction of Al-containing materials grown by HVPE, has not been reported because of the complexity of their growth. This paper presents the solar cell applications of AlInGaP grown via HVPE using aluminum trichloride (AlCl 3 ) as a precursor. Increasing the partial pressure of AlCl 3 increased the Al composition in the AlInGaP layers. Although high concentrations of Si and O impurities were detected within the HVPE-grown AlInGaP layers, the crystals were found to be of a quality that could be used in III-V solar cells. By using AlInGaP as a passivation layer in InGaP single-junction solar cells, the current density was improved because of a reduction in the surface recombination loss. A conversion efficiency of 15.4% was achieved for the InGaP single-junction solar cells measured under airmass 1.5 global solar spectrum illumination. Moreover, we developed 26.9% efficient InGaP/GaAs dual-junction solar cells, the highest conversion efficiency in reported cells grown via HVPE. This result demonstrates an improvement in the performance of HVPE cells by introducing Al-containing materials.

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