Photopyropiezoelectric elastic bending method

Abstract

A method of investigation of semiconductors and metal–semiconductor structures based on two techniques: The elastic bending technique and pyropiezoelectric (PPE) technique was presented. The method was demonstrated on a metal–semiconductor–metal (MSM) structure, which is attached to a PPE detector. Two different ac voltages can be measured: One on the electrodes of MSM structure—the ac-photovoltage, and another on the electrodes of the PPE detector—the PPE voltage. The ac photovoltage is a consequence of the photogenerated plasma processes in the sample (MSM structure). Photogenerated plasma waves in a semiconductor are followed by the thermal and elastic waves (the elastic bending). Then, the pyroelectric voltage is a consequence of the thermal processes and the piezoelectric voltage is a consequence of elastic bending in the sample-PPE detector system. A theoretical model for a metal–semiconductor–metal-pyro(piezo)electric system is given including the space-charge regions and electronic states on the semiconductor surfaces, thermodiffusion, thermoelastic, and electronic deformation effects in a semiconductor. The photoelectric and pyropiezoelectric effects are investigated by analyzing the ac voltages as a function of the modulation frequency of excitation beam.