The TEES system at WSU is applied to study point defects in wide gap semiconducting and semi-insulating opto-electronic materials, including CdTe, CdZnTe, CdTeSe, Ga2O3, BiI3. In a typical TEES measurement, the system is cooled down to 20 K where the defects are filled by optical excitation. Release of the trapped charge carriers upon heating can provide information about trap parameters, e.g., energy and capture cross section. The system can also perform thermally stimulated current (TSC) and persistent photoconductivity (PPC) measurements.
This system can perform measurements in the 10 – 350 K range, with diode excitations for trap filling (e.g., 365 nm, 385 nm, 400 nm, 780 nm, and 950 nm). The sample can also be biased during trap filling.