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High uniformity of the thickness and net donor concentrations (Nd-Na) in 100 mm diameter β-Ga2O3(001) epitaxial wafer prepared by halide vapor phase epitaxy was demonstrated. An epitaxial wafer grown on a substrate with a miscut angle near 0° generated a specific epitaxial region with a lower growth rate and a higher Nd-Nathan the rest of the region, which deteriorated the wafer uniformity. In contrast, epitaxial wafers prepared on substrates with a miscut angle of –0.1° suppressed the occurrence of the specific epitaxial region, and an average thickness after chemical mechanical polishing of 10.6 μm with 5% tolerance and an average Nd-Nawithout intentionally doping of 1.1 × 1016 cm−3within 7% tolerance were successfully obtained.

AbstractThis paper considers a cooperative fuzzy game with nplayers and ralternatives called a multi-alternative fuzzy game. Considering the non-homogeneity among players, we pro-pose a new value function on a class of these games, which means evaluation values for the game by players. Furthermore an axiom system is proposed on which the new value function is based. Finally we give a numerical example in which the new value is compared with traditional values.

Here, we investigate the dislocations in b-Ga2O3 single crystals grown by edge-defined film-fed growth (EFG) and halide vapor-phase epitaxy (HVPE) using synchrotron X-ray topography. The (001)- and ($\bar{2}01$)-oriented crystals grown in the [010] direction by EFG exhibited dislocations along the [?]010[?] direction with some dislocations oriented in a line; in addition, wandering dislocations were observed on the (001) surface. Based on the invisibility criterion, the Burgers vector of some dislocations was determined to be [?]010[?]. On the other hand, in the (001) film grown by HVPE over the EFG substrate, threading dislocations propagating in the [001] direction were observed. Furthermore, it was found that the dislocations on the substrate grown by EFG were inherited by the film formed by HVPE: a dislocation was generated in the film grown by HVPE at both ends of the void defects in the substrate grown by EFG.

Diamond/Si bonding interface with an entire contact area and high thermal stability is achieved by surface activated bonding method. The fabrication of diamond field-effect transistors (FETs) on the diamond bonded to Si is demonstrated. The FET exhibits clear saturation and pinch-off characteristics. A 5 nm thick SixCx-1layer was formed at the interface with annealing at 1000 °C. The layer was formed by the inter-diffusion of carbon and Si atoms near the bonding interface, which plays a role of residual stress relaxation between diamond and Si. These results suggest that diamond/Si heterostructures are applicable for combining diamond devices with Si LSI.

On the surface of as-grown b-Ga2O3 single crystals that are cut and polished, we found nanometer-sized grooves elongated in the [001] direction. We confirmed that these grooves terminate within the crystals in the [010] direction. This proves that the grooves are different from micropipes penetrating crystals. Their typical length and width are 50-1200 nm in the [001] direction and [?]40 nm in the [100] direction, respectively. The grooves tend to form an array in the [001] direction. The type of nanometer-sized grooves should be essentially different from etch pits.