"Dual-wavelength Photo-Hall effect spectroscopy of deep levels in high resistive CdZnTe with negative differential photoconductivity
Abstrakt
Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (Cd1-xZnxTe) are well known as important semiconductors with applications in X- and gamma-ray detection, solar cells and electro-optic modulators. Many of their physical properties are controlled by energy levels within the bandgap, deep levels (DLs), associated with native defects, impurities, and defect complexes.
Such defects create recombination and trapping centers in the energy band gap capturing electrons and holes created by radiation and depreciating the performance of the detector. In this presentation we introduce a novel spectroscopy method, Photo-Hall Effect spectroscopy with double wavelength illumination (DWPHES).
The method is derived from well-known Photo-Hall effect measurements, where additional laser illumination with different wavelength is used. DWPHES allows us direct observation of DLs which cannot be observed from PHES, furthermore, it was ascertained that additional laser light exposure improves the quality of the Hall voltage.
A number of DLs was discovered by DWPHES and interpreted, either levels above or below Fermi energy. After analyzation of numerous Hall signal spectra and flux dependencies, the key principles of PHES and DWPHES measurements were formulated.
The most of DLs observed by DWPHES were consistently verified by PL spectroscopy.