Takashi Udagawa

Growth of GaInN by Raised-Pressure Metalorganic Vapor Phase Epitaxy

GaInN films with different In compositions were grown using a raised-pressure metalorganic vapor phase epitaxy (MOVPE) system operated from 100 to 200 kPa. A precise X-ray diffraction study showed that the In composition increases with an increasing pressure during growth, which is consistent with the result of a thermodynamic analysis.

Blueish green photoluminescence from nitrided GaAs(100) surfaces

Abstract Optical and structural studies were made on the Si-doped (100)GaAs surfaces nitrided at a temperature between 650° and 750°C for 15 min in the flowing NH 3 gas. The wavelength of photoluminescence (PL) spectra were observed to be shortened from 820 nm of the GaAs nitrided at 650°C with increasing nitridation temperature. Blueish green PL with wavelengths of approx. 490 nm and 470 nm were emitted from the nitrided surfaces at 700° and 750°C, respectively. Results of AES and SIMS indicated that the surfaces are nitrided as GaAs 1− x N x , (0 x ≤1) alloy layer, and the nitrided region also tended to increase as the temperature raised. High-resolution transmission electron microscopic (HRTEM), transmission electron diffraction (TED) and energy dispersive X-ray (EDX) results showed that films peeled off from the nitrided surfaces consisted mainly of hexagonal, wurtzite-type gallium nitride (GaN) with stacking faults and microtwins.

Organometallic chemical vapor deposition growth of heterostructure of wide band gap and transparent boron phosphide on silicon

A boron phosphide (BP) layer was grown on the (111) Si substrate by atmospheric pressure organometallic chemical vapor deposition (MOCVD) using triethylboran ((C2H5)3B) and phosphine (PH3) sources. By transmission electron diffraction analysis, the transparent BP layer was found to grow on (111) Si with the following orientation: (111), -Si//(111), -BP. The MOCVD-grown BP layers exhibited transparency under fluorescent light illumination. Reflected light color was observed to vary depending on the thickness of the BP layer. The refractive index (n) of the heteroepitaxial (111) BP layer was revealed to decrease from 3.16 at a wavelength (λ) of 350 nm to 2.77 at λ of 750 nm. The extinction coefficient (k) corresponding to n at λ of 350 nm was 0.19. Refractive index (n) and k at λ of 350 nm gave 9.95 as the real part of the complex dielectric constant of the MOCVD-grown BP layer. The optical evaluation indicated that BP is applicable as a transparent III-V semiconductor layer for forming heteroepitaxial structures with Si.

Effect of Cr Concentration on Electrical Properties of Cr-Doped Semi-Insulating GaAs Substrates

The chromium concentration in semi-insulating GaAs substrates and its distribution along Cr-doped ingots have been measured by flameless atomic absorption spectrophotometry. When the Cr concentration is lower than a certain value, the Cr distribution can be approximated by the normal freeze equation. Whereas at higher Cr concentrations, the measured distribution deviates from the equation probably due to Cr precipitation. The Cr concentration is found to be closely correlated with leakage currents in the substrates and with activation efficiencies of 28Si ions implanted directly into the substrate.