Achieving detector-grade CdTe(Cl) single crystals through vapor-pressure-controlled vertical gradient freeze growth

Fig. 1. The schematic figure of the crystallization process. (a) Schemes for growing CdTe(Cl) crystals by vapor-pressure-controlled vertical gradient freeze growth; (b) CdTe(Cl) ingot and cross-section; (c) Infrared images of CdTe(Cl) sample; (d) Histogram of Te inclusions size distribution.Fig. 2. Optical properties of CdTe(Cl) crystals. (a) FTIR transmittance spectra recorded from 4000 cm−1 to 500 cm−1; (b) UV–Vis-NIR transmission spectra, inset is band gap fitting result based on Tauc model; (c) Normalized photoluminescence spectra at 77K.Fig. 3. Electrical properties of CdTe(Cl) crystals. (a) A typical current-voltage (I − V ) curve at a ±0.1V bias; (b) Histogram of resistivity distribution for 5 CdTe devices; (c) Laser-induced transient current waveforms recorded as voltage increases from 160V to 200V, where the dashed line indicates transit time; (d) Dependence of the electron drift velocity on electric field strength.Fig. 4. Spectral response of CdTe(Cl) planar detector to α particle. (a) Typical 241Am@5.48MeV α particle energy spectra; (b) Mobility lifetime fitting for electron according to the Hecht equation based on the α particle spectra.