Electric and Electroluminescent Properties of the Surface Layers of ZnS : Mn, Cu, Cl Films

Current (I)-voltage (V) and capacitance (C)-voltage (V) characteristics of the vacuum-evaporated films of ZnS : Mn, Cu, Cl were measured. I-V curves were similar to the diode characteristics. And its cut-off voltage was about 1.1 volts. C^∞V relations also gave a diffusion potential 1.1 volts. However, it seems that these characteristics are not due to the metal-ZnS contact but to the surface structure of films (Cu_S-ZnS junction), since differences in cut-off voltage or diffusion potential were not observed either in Au or in Cu electrodes. The band gap of the excessive Cu layer was estimated at about 1.27 eV. That is to say, an excessive Cu is thought to exist as Cu_S on the surface of ZnS : Mn. Cu, Cl films, and p-Cu_S-n-ZnS heterojunctions are formed at the surface layer of ZnS : Mn, Cu, Cl films. At the forward-biased junctions, holes are injected into n-ZnS phase from p-Cu_S phase, and consequently EL emission with 580 mμ peak can be observed by Mn^ which involves the energy transfer from Cu^+ centers to Mn^ centers. EL emission localized at the anode in gap cells and EL emission in the forward-biased sandwich cells can be explained by the model of heterojunction mentioned above. On the other hand, EL emission localized at the cathode in gap cells and EL emission in the reversebiased sandwich cells under the high voltage are thought to be due to the usual mechanism of impact excitation

Distribution Patterns of Strain and Dislocations Around Indented Areas in Germanium Crystals as Observed by X-Ray Topography

Three-dimensional distribution patterns of the strain and dislocations developed around indented areas in germanium crystals are observed as a function of the deformation temperature between 20°and 700℃ by use of X-ray diffraction topography. The size of the deformed region around an indented area is found to have a relationship with the hardness value, i.e., the former begins to increase abruptly at the temperature where the latter begins to decrease abruptly as the deformation temperature is raised. The areas indented at high temperatures are subjected to two kinds of treatments : One group of areas is brought to room temperature after indentation while an indenter load is applied, and the other is cooled after an indenter load has been removed. Rearrangement of dislocations takes place during annealing of specimens. Annealing brings about a configuration of dislocations lying parallel to directions