Epitaxial Lateral Overgrowth of {11-22} InGaN Layers Using Patterned InGaN Template and Improvement of Optical Properties from Multiple Quantum Wells

We report the growth and characterization of thick, completely relaxed {11-22}-oriented InGaN layers using epitaxial lateral overgrowth (ELO). Although it was difficult to grow ELO-InGaN layers on patterned GaN templates, we succeeded in growing ELO-InGaN layers on a patterned InGaN template. The full width at half maximum of the X-ray rocking curve of ELO-InGaN on the InGaN templates was less than that of non-ELO InGaN. The photoluminescence intensity of InGaN/GaN multiple quantum wells on ELO-InGaN was approximately five times stronger than that on the {11-22} GaN template

Growth of 300-nm-thick epitaxial AlInN films on a semi-relaxed c-plane GaInN template by metalorganic chemical vapor deposition

Metalorganic chemical vapor deposition of approximately 300-nm thick epitaxial AlInN films with different alloy compositions was performed using a semi-relaxed c -plane GaInN template as an underlying substrate. The GaInN template consisted of a Ga _0.98 In _0.02 N film on a facet-structured GaN film formed on a c -plane sapphire substrate by the epitaxial lateral overgrowth technique, and its surface was treated with the chemical-mechanical polishing. It was observed that an Al _0.835 In _0.165 N film grown with an in-plane tensile strain exhibited a relatively smooth surface whereas an Al _0.781 In _0.219 N film grown with an in-plane compressive strain exhibited a granular morphology owing to a columnar polycrystalline structure. This phenomenon was quite similar to that observed for AlInN films grown non GaN/sapphire templates (GaN templates); therefore, it was speculated that the microstructure variation might have been caused by the in-plane compressive strain generated in AlInN films on the GaInN template in the same way as on GaN templates or FS-GaN substrates

Characterization of GaN based Schottky UV detectors in the vacuum UV (VUV) and the soft X-ray (SX) region (10-100 nm)

Responsivity spectra of GaN based Schottky type ultraviolet (UV) photodetectors with transparent electrode from the Vacuum Ultraviolet (VUV) region to soft X-ray (SX) region (10-100 nm, 124-12.4 eV) are described for the first time. The calculated transmittance of 10 nm-thick transparent Ni/Au electrode from the transmittance of Ti/Au membrane is about 0.5-0.7 in the VUV and SX region (10-100 eV). Thus it is considered that the 10-nm-transparent Ni/Au electrode is thin enough to transmit VUV and SX light into the transparent electrode. The value of responsivity in the SX region (at 13 nm) is about 0.05 A/W

Impact of thermal treatment on the growth of semipolar AlN on m-plane sapphire

The interest in semipolar orientations has been increasing because the reduced piezoelectric field can improve the performance of nitride-based optoelectronic devices. However, the crystalline quality of semipolar AlN on m-plane sapphire is still not good enough to realize light emitters with sufficiently high efficiency. We performed high-temperature annealing on AlN on m-plane sapphire to improve the crystalline quality. For (10-1-3) and (11-22) AlN on m-plane sapphire, the crystalline quality improved as the annealing temperature was increased up to 1700 °C, whereas beyond 1750 °C the AlN layer started to deteriorate and desorb. The crystalline quality was further improved by additional growth of AlN. In addition, X-ray rocking curve measurements and transmission electron microscopy confirmed that the density of stacking faults was reduced after the additional growth of AlN