Surface electronic structure investigations of CdTe and Cd{sub}0.98Fe{sub}0.02Te via the surface photovoltage spectroscopy method

摘要

Surface electron properties investigations have been carried out for the triple compound Cd{sub}0.98Fe{sub}0.02Te with a modified Kelvin method of the surface photovoltage measurement with a constant illumination. Measurements of the surfacephotovoltage spectroscopy (SPS) have been performed in the temperature range between 140 and 300 K at the pressure of 10{sup}-5Pa. For comparison, similar investigations have been carried out for high-purity CdTe crystals. The measurements have been donefor the surface polished and cleaved in a vacuum of 10{sup}-8 Pa. From the changes of their surface photovoltage as a function of the wavelength of the incident illumination, the energy values of the electron levels E{sub}t1, E{sub}t2, E{sub}t3, E{sub}t4and E{sub}Fe, have been determined. The E{sub}Fe, level (0.95 eV above E{sub}v) is connected with the introduction of iron into the CdTe matrix. The surface potential barrier value and its change with temperature has been determined. The energetic schemes of the CdTe and Cd{sub}0.98Fe{sub}0.02Te surface layer are presented.