Masateru Yamamoto

Complete Polarization Control of 12×8-Bit Matrix-Addressed Oxide-Confined Vertical-Cavity Surface-Emitting Laser Array

The authors have shown complete polarization control of a 12×8-bit matrix-addressed oxide-confined vertical-cavity surface-emitting laser (VCSEL) array, which has an unstrained active region emitting at 780 nm. By using a combination of an elliptical-shaped post structure fabricated on misoriented substrate and upper p-side metal lines elongated in the substrate off-direction, we observed complete polarization pinning in an index-guide type array device. All of the VCSELs in this array lased in a fundamental transverse mode and linearly polarized along the direction.

GaAs (001) surface balanced with arsine partial pressure in metalorganic chemical vapor deposition reactor observed by surface photoabsorption

Abstract We measured surface photoabsorption signals from As adsorbed surfaces of GaAs (001) substrates in a reactor of metalorganic chemical vapor deposition (MOCVD) under various partial pressures of AsH3. Desorption of As atoms from the surface was balanced with adsorption of As atoms under AsH3 partial pressure. We found that the surface conditions varied as a function of the partial pressure and the temperature of the substrate. Comparing the experimental results with a multi-layer Langmuir adsorption model, we determined the phase boundaries of the surface structures under MOCVD conditions at temperatures between 500 and 700°C. One of the boundaries was assigned to the boundary between (2 × 4) and c(4 × 4), and the other to that between c(4 × 4) and a surface of excess As.

In-situ observation of Ga adsorption during TMGa exposure on GaAs(001) surfaces with various As coverages

Abstract We measured transients of surface photoabsorption signals during TMGa exposure on c(4 × 4)-like, 2 × 4-like and Ga-terminated GaAs(001) surfaces in the MOCVD reactor. Ga-containing species were continuously deposited during TMGa exposure on Ga-terminated surfaces. On the other hand, self-limiting deposition was observed on c(4 × 4)-like and 2 × 4-like surfaces. The growth thickness in one cycle of ALE process on the 2 × 4-like surface was 0.7–0.8 compared to that on the c(4 × 4)-like surface. The stable duration of the SPA signal under TMGa exposure was longer than the residency time of methyl groups on the surface which was obtained from the transients during purge after TMGa exposure. Hence the methyl groups are continuously supplied to the surface by decomposition of TMGa during the exposure period under self-limiting condition.