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Nitride-based p-i-n ultraviolet (UV) photodetectors with a low-temperature (LT) GaN interlayer were proposed and fabricated. Compared with a conventional GaN p-i-n photodetector, it was found that both the dark current and ideality factor of the p-i-n photodetector with an LT-GaN interlayer became larger whereas the UV-to-visible rejection ratio became smaller because of the poor crystal quality of the LT-GaN interlayer. However, the responsivity of the GaN p-i-n photodetector with an LT-GaN interlayer was larger than that of the conventional GaN p-i-n photodetector under a high reverse bias because of the carrier multiplication effect and/or internal gain that originated from the defect levels. [ABSTRACT FROM AUTHOR]

Abstract: High density InN/GaN nanodots were grown by pulsed mode (PM) metal–organic chemical vapor deposition (MOCVD). InN nanodots density of up to ∼5×1010 cm−2 at a growth temperature of 550°C was achieved. The high diffusion activation energy of 2.65eV due to high NH3 flow rate generated more reactive nitrogen adatoms on the growth surface, and is believed to be the main reason for the growth of high density InN nanodots. In addition, an anomalous temperature dependence of the PL peak energy was observed for high density InN nanodots. The high carrier concentration, due to high In vacancy (V In) in the InN nanodots, thermally agitated to the conduction band. As the measurement temperature increased, the increase of Fermi energy resulted in blue-shifted PL peak energy. From the Arrhenius plot of integrated PL intensity, the thermal activation energy for the PM grown InN nanodots was estimated to be E a∼51meV, indicating strong localization of carriers in the high density InN nanodots. [ABSTRACT FROM AUTHOR]

Abstract: Nitride-based GaN/In0.12Ga0.88N heterostructure field effect transistors (HFETs) with semi-insulating Mg-doped GaN current blocking layers were successfully fabricated. The as-grown layers exhibited a very smooth surface. The DC characteristics of these HFETs were substantially improved over those previously reported. Devices with a 0.75μm gate length showed a maximum drain current (IDS) of 421mA/mm, and a maximum gm of about 85.6mS/mm at VGS between -0.5 and -3V. The device which had a very good pinch-off with source–drain (S–D) leakage current was negligibly small, in the range of 10-1–10-2mA/mm. The RF characteristic of devices showed the current gain cutoff frequency, fT, was 7.45GHz and the maximum oscillation frequency, fMAX, was 12.36GHz. [Copyright &y& Elsevier]

Nitride-based AlGaN/GaN heterostructure two-dimensional electron gas photodetectors have been successfully fabricated by low-pressure metalorganic vapor phase epitaxy on sapphire substrate. By using such an AlGaN/GaN heterostructure, we could significantly reduce the recombination of photogenerated carriers and thus achieve extremely high photodetector responsivity due to the use of AlGaN/GaN heterostructure. With an incident light wavelength of 270 nm, it was found that the AC responsivity could reach 8.7 × 106 A/W. [Copyright &y& Elsevier]