CdTe polycrystalline films for X-ray digital imaging applications

CdTe films were grown onto amorphous substrates by electron beam deposition (EB) and by horizontal and vertical physical vapor deposition (HPVD and VPVD). The films were characterized by X-ray diffraction, scanning electron microscopy (SEM) and by measuring their electrical resistivity and response to X-rays. A 4-μm-thick layer deposited by EB had uniform grain size, preferred growth orientation of (1 1 1). However, the films did not have any response to X-rays since the resistivity of the layer was only 104 Ω cm. The grain distribution, grain size and roughness of films grown by HPVD were nonuniform. VPVD gave uniform films 35 to 150 μm thick, grain size between 5 and 25 μm, preferred growth orientation of (1 1 1), resistivity of 106 Ω cm and linear response to X-rays. Correlations between texture and grain size with substrate temperature were established.