Ryuichi Ueda

Continuous operation over 1500 h of a PbTe/PbSnTe double-heterostructure laser at 77 K

Continuous operation over 1500 h at 77 K has been achieved by use of a PbTe/Pb0.93Sn0.07Te double‐heterostructure laser which was grown using the liquid‐phase‐epitaxy method. The cw threshold current changed only about 3% during the first 200 h. It is concluded that the lifetime of PbTe/PbSnTe double‐heterostructure lasers at 77 K is fundamentally very long.

Determination of oxygen concentration profiles in silicon crystals observed by scanning IR absorption using semiconductor laser

Concentration profiles of interstitial oxygen in silicon crystals were determined by scanning IR absorption using PbTe‐Pb0.82Sn0.18Te semiconductor laser with the wavelength of 9.04±0.02 μm. IR beam was collimated to be 200 μm in diameter. Czochralski‐grown crystals showed a local concentration fluctuation of about 1.8×1017 cm−3 from the average of 1.1×1018 cm−3. This fluctuation corresponds to an oxygen striation in the silicon crystal.

Misfit dislocations in PbTe-PbSnTe heterojunction

Abstract Misfit dislocations at the heterojunction of PbTe-PbSnTe layers grown by liquid phase epitaxy have been investigated by etch pit studies. The linear density of misfit dislocations along the 〈100〉 direction parallel to the heterojunction was in good agreement with the predicted value. This agreement indicates that the strain due to lattice mismatch between PbTe and PbSnTe is completely relieved by the introduction of misfit dislocations. It has been shown from the distribution of etch pits, electron probe analysis, and calculations, that the misfit dislocations spread around the heterojunction in the region determined by Sn self-diffusion during epitaxial growth.

Far-infrared cyclotron mass of CdxHg1−xTe near the Λ6 - Λ8 crossover

Abstract The far-infrared cyclotron resonance of electrons in Cd.176Hg.824Te with low carrier concentration has been measured by a magneto-reflectance method in the wavelength region of 45 μm ∼ 150 μm at 4.3 K. The effective-mass is determined to be 6.2 x 10-3 mo.