A vertical-type Schottky photodetector based on a (100)-oriented β-Ga2O3 substrate has been fabricated with simple processes of thermal annealing and vacuum evaporation. The photodetector exhibited a rectification ratio higher than 106 at ±3 V, and showed deep-ultraviolet-light detection at reverse bias. The spectral response showed solar-blind sensitivity with high photoresponsivities of 2.6–8.7 A/W at wavelengths of 200–260 nm. These values were 35–150 times higher than those derived assuming the internal quantum efficiency to be unity. This fact is attributed to the carrier multiplication occurring in the highly resistive surface region that is subject to a high internal electric field of about 1.0 MV/cm at the reverse bias of 10 V.

We fabricated β-Ga2O3 photodiodes with a Au Schottky contact on a single crystal substrate and investigated the effect of postannealing on the electrical and optical properties of the photodiodes. The ideality factor improved to near unity by annealing at temperatures above 200 °C; however, the reverse leakage current remained nearly unchanged. The responsivity in the wavelength region below 260 nm was enhanced dramatically by a factor of more than 102 after annealing at 400 °C resulting in maximum responsivity of 103 A/W, accompanied with a contrast ratio of about six orders of magnitude between the responsivities at 240 and 350 nm.

Rho-associated kinase (ROCK) regulates reorganization of actin cytoskeleton. During adipogenesis, the structure of filamentous actin is converted from long stress fibers to cortical actin, suggesting that the ROCK is involved in adipogenesis. Two ROCK isoforms have been identified: ROCK-I and ROCK-II. However, pharmacological inhibitors of ROCK cannot distinguish two ROCK isoforms. In the present study, we examined the role of ROCK in adipogenesis and actin cytoskeleton using genetic and pharmacological approaches. Y-27632, which inhibits the activity of both ROCK isoforms, enhanced adipogenesis through the up-regulation of adipogenic transcription factors in 3T3-L1 cells.

An oxide semiconductor of -Ga 2 O 3 has a natural solar-blind sensitivity due to its large bandgap of 4.8 eV. To evaluate its potential, a flame detector was fabricated using its conductive single crystal substrate applying a simple method without epitaxy and vacuum processes. The structure is a poly(3,4-ethylene dioxythiophene) complex with polystyrene sulfonic acid (PEDOT-PSS) Schottky contact/a semi-insulating layer of -Ga 2 O 3 /n-type region of -Ga 2 O 3 /an In ohmic contact. The spectral response of the detector exhibited a large 250-to-300-nm rejection ratio of 1:5 Â 10 4 and an external quantum efficiency of 18% at 250 nm. The device successfully detected a flame by distinguishing 1.5 nW/cm 2 solar-blind light from the flame under a strong fluorescent lamp illumination without any visible-cut filters. This result encourages the fabrication of practical -Ga 2 O 3 -based flame detectors.