| 摘要 |
Impurity centres are produced in a pure body of cadmium sulphide for a photoelectric cell by immersing it in a large quantity of a pulverulent mixture of cadmium sulphide and the desired impurity, the proportions of each constituent being equal to or slightly greater than that which is desired in the body, the whole assembly then being heated to the point where an equal distribution of the impurity occurs by thermal diffusion, e.g. 500 DEG to 600 DEG C. The quantity of pulverulent material should be about 100 times that of the body to be treated, and it may be diluted by an inert material to prevent the powder from adhering to the body. In one example, the pulverulent mixture consists of 99.1 per cent pure cadmium sulphide, 0.8 per cent cadmium chloride, 0 04 per cent copper sulphide and 0.06 per cent nickel chloride; the copper sulphide may be replaced by copper chloride containing the same quantity of copper. In another example, the mixture consists of 60 per cent cadmium sulphide, 39.9 per cent cadmium selenide, 0.05 per cent copper chloride, 0.01 per cent gold chloride, 0.01 per cent lead chloride and 0.02 per cent silver chloride; the chlorides may be replaced by other salts containing the same quantity of metals. The impurity centres may be introduced in two stages by separate heatings in different pulverulent mixtures, each heated to different temperatures.
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