Cadmium telluride thin-film detectors of nuclear radiation

Semiconductor detectors for X-ray and γ radiation are developed based on thin cadmium telluride (p-n-CdTe) films possessing a columnar structure. The detector structures are formed on molybdenum substrates by CdTe sublimation and magnetron sputtering of cadmium. The p-CdTe films have a thickness of d=30–150 μm and a resistivity of ρ≥103–107 Ω cm. The single crystal grains in the films have an average size of 50–100 μm and are oriented perpendicularly with respect to the Mo substrate. In comparison to the usual single crystal CdTe detectors, the proposed thin-film single crystal CdTe detectors possess a more perfect structure, since the grain boundaries act as effective sinks for defects. The energy resolution of the new generation of CdTe detectors reaches ∼5 keV for the 59.6 keV line of 241Am at room temperature.