K. Matsuura

Defect-induced emission band in CdTe

We report on a distinct correlation between the 1.47 eV emission band and the dislocation density in bulk CdTe. The 1.47 eV band intensifies around the high-dislocation area (lineage structure) and at the position just on dislocation bundle. On the other hand, the 1.47 eV band was hardly observed in the low-dislocation area (etch pit density less than 2 × 105 cm-2) or at the position away from the dislocation bundle. Furthermore, the 1.47 eV band was intensified by γ-ray irradiation of 1.7 × 107 Gy, which produced a great number of Frenkel defects. It was shown that the 1.47 eV band is related not only to an extended defect such as a dislocation, but also to a point defect such as a Frenkel defect. These results suggest that the strain field induced in the vicinity of the defects is responsible for the recombination center of the 1.47 eV band.

Thermoluminescence in ZnS Crystals Fired in Zinc or Sulfur Vapor

Photoluminescence spectra, glow curves of blue and green emissions and the thermal bleaching of the 2.3eV absorption band (due to a single-negatively charged sulfur vacancy) have been measured on ZnS crystals heated in sulfur or zinc vapor. It has been found that the as-grown specimens show the self-activated blue emission (470 nm) and a weak green emission. The specimens heated in zinc or sulfur vapor show mainly the copper blue (452 nm) and the copper green (545 nm) emissions. The temperatures of glow peak maxima are obtained as 133,165,207 and 235K with a heating speed of 1 deg·sec -1 . The emission of the 133 K glow peak consists of the copper blue emission and the others of the self-activated blue or the copper green emission. The 2.3 eV band is bleached thermally accompanied by the 133K glow emission. It is concluded that the 133 K glow peak is due to positive holes released from hole trapping centers while the others due to electrons from electron trapping centers.

A Hole Trap Center Related to the 2.361 eV Bound Exciton Emission in ZnTe Single Crystals

The heat-treatment effects of ZnTe single crystals which contain a low concentration of Te inclusions were investigated by photoluminescence, optical-absorption and admittance spectra measurements. A correlation between the 2.361 eV bound exciton emission and hole traps located at 0.39 eV above the valence band is reported.

Effects of Uniaxial Stress on the Electrical Properties in CdS Single Crystals

Measurements of the conductivity and the Hall effect in high conductivity CdS crystals have been made at liquid nitrogen temperature, under the compressional uniaxial stress applied parallel or perpendicular to the c -axis. It has been found that the change in the conductivity induced by the applied stress is substantially due to the change in the electron mobility. The mobility decreases with increasing the stress when the mobility under zero stress is near the intrinsic mobility, while the mobility increases with the stress when the mobility under zero stress is smaller than the intrinsic mobility. This behavior is explained in terms of the negative stress coefficient of the intrinsic mobility, (-2.9±0.5)×10 -11 dyn -1 cm 2 and the positive coefficient of the extrinsic mobility, (2.7±0.3)×10 -10 dyn -1 cm 2 .

Circuit for extension of an interrupt input of a personal computer PC8001mkII

A circuit is described which extends an interrupt input of a personal computer PC8001mkII to multiple interrupt inputs using a daisy‐chain approach, where prioritized interrupts up to 128 levels may be available by providing additional wait states and an interrupt look‐ahead circuit. The circuit presented in this note may be applied to other computers with some slight modifications.