High-performance GaInN-based solar cells with high open-circuit voltage, high short-circuit current density, and good fill factor have been obtained using a combination of two different GaInN superlattice structures. The GaInN barrier thicknesses (3 and 0.6 nm) in both superlattice structures were optimized, resulting in a thick GaInN-based active layer with a low pit density in the device. The conversion efficiency is approximately 2.5% under a solar simulator of air mass 1.5G and an irradiation intensity of 155 mW/cm 2 .

We found different behaviors of misfit dislocations in a Ga0.83In0.17N single layer and in Ga0.83In0.17N/Ga0.93In0.07N superlattices, both on GaN substrates. In the case of the single layer, misfit dislocations were formed at the GaInN/GaN interfaces and extended through the GaInN layer to the surface. In contrast, the misfit dislocations in the superlattices are bent laterally at interfaces between the Ga0.83In0.17N and Ga0.93In0.07N layers. In addition, most of the dislocations do not reach the surface owing to the formation of dislocation loops. As a result, the dislocation density at the surface of the GaInN superlattice sample was 5×107 cm-2.

We report on the electrical properties of AlGaN/GaInN heterostructures fabricated with various InN molar fractions from 0 to 0.60 in GaInN on a GaN template. The sheet carrier density of the AlGaN/GaInN heterostructure monotonically increased with increasing InN molar fraction in GaInN, reaching 5.0 Â 10 13 cm À2 at an InN molar fraction of 0.60. The Al 0.30 Ga 0.70 N/Ga 0.40 In 0.60 N heterostructure exhibited static field-effect transistor (FET) characteristics.

Epitaxial growth of GaN films at a low temperature of 800 °C was studied in radical-enhanced metal-organic chemical vapor deposition, focusing on the discharge region of the plasma of a mixture of N2 and H2 gases. The effect of plasma confinement on the growth is crucial for realizing high crystal quality of grown GaN films, owing to the suppression of plasma-induced damage and decomposition of gallium precursors in the gaseous phase. By confined plasma in the discharge region using the plasma shield plates made of metal with multiple small holes effectively, GaN with a relatively flat surface was grown under conditions of higher V/III ratios. Epitaxial growth of GaN films was achieved by modifying the plate design and controlling the high V/III ratio using both the plasma-excitation power and the Ga precursor flow rate.