Adaptive photo-EMF detectors based on CdTe and their solid solutions
The complex measurements of V(Ti)-doped CdTe (crystals and films) and their solid solutions were carried out. This allowed to establish the nature and energy structure of the intrinsic defects and impurity centers and to propose the micromechsnism of photo-EMF effect. The adaptive photodetectors based on these crystals and CdTe polycrystalline films were developed.
Effective broadband detection of nanometer laser-induced ultrasonic surface displacements by CdTe:V adaptive photoelectromotive force detector
Results of experiments studying the utilization of adaptive CdTe:V photoelectromotive force (photo-EMF) detector for high-sensitivity broadband detection of laser-generated ultrasound are presented. Unlike widely used GaAs photo-EMF detectors, the devices used here demonstrate no significant electron-hole competition. This ensures effective detection of ≅1 nm surface displacements with ≅0.1 mW of the signal beam power in 10 MHz detection frequency band, even in simple transverse detector configuration. For the wavelength of λ=852 nm used in the experiments, the dielectric cutoff frequency of a typical device was approaching 1 MHz. This, in principle, enables monitoring of as-processed objects moving with in-plane velocities up to 10 m/s.
Annealing behavior of bound exciton lines in high quality CdTe
Annealing behavior of shallow donor‐bound and acceptor‐bound exciton lines in CdTe crystals grown by the Bridgman method was investigated by high‐resoluton photoluminescence measurements at 4.2 K. The intensity of the neutral acceptor‐bound exciton line (A0X) at 1.5896 eV, which was commonly observed in p‐type CdTe, drastically decreased by annealing under Cd saturated atmosphere. By further subsequent annealing under Te saturated atmosphere, the A0X line recovered again. On the other hand, the intensity of the neutral donor‐bound exciton line increased by annealing under Cd saturated atmosphere and decreased by the further annealing under Te saturated atmosphere. It was found that this change in the photoluminescence lines by the annealing process was reversible. These results strongly suggest that the A0X line at 1.5896 eV can be ascribed to the recombination of excitons trapped at Cd‐vacancy/donor‐impurity complexes.