| 摘要 |
PURPOSE:To detect an ionization current with high efficiency, by changing the intensity of the n-type region formed to a low specific resistance p-type CdTe single crystal in accordance with the intensity of the energy of a radiation source. CONSTITUTION:An n-layer 2 is formed, for example, by applying Al to one surface of a low specific resistance p-type CdTe single crystal wafer 1 by vacuum vapor deposition and subsequently heating said wafer 1 for a predetermined time to thermally diffuse Al while an ohmic electrode 3 is formed by applying an aqueous gold chloride solution to the other surface of the wafer 1. For example, gamma-rays incident to the n-layer 2 in this constitution lose energy in the wafer 1 to form an electron-hole pair. This electron-hole pair becomes an output current since an electron is taken out on the side of an Al electrode and a hole is taken out on the side of the Au electrode 3 by the diffusion potential in the depleted layer formed by the pn junction being the boundary of a p-layer and the n-layer. This current is amplified by an I/V converting amplifier 5 through a lead wire 6 to be converted to voltage. The depth of the n-layer is increased with respect to high energy radiation and reduced with respect to low energy radiation. By this method, an ionization current can be taken out with high efficiency.
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