The Research of Piezo Phototron Effect in A2B6 Film Structures

Abstract

The paper presents the results of the study of a piezo phototron effect in hetero structures based on A2B6 films. The field of study of the piezo phototron effect in semiconductor thin films is new. The use of materials that have several properties at the same time, namely semiconductors, piezoelectrics and photoelectric properties, allows us to create a fundamentally new class of semiconductor devices, especially in the field of sensors and photovoltaics. Obtaining films of the A2B6 group, which include CdS, CdTe, CdSe, ZnS, ZnSe, ZnO with an existing piezoelectric effect, is an urgent task. In this work, the object of study is diode structures based on them. Namely, CdS films were grown by thermal evaporation on a flexible molybdenum substrate. A thin layer of degenerate CuxS semiconductor was deposited on top of the CdS films, which allowed it to form a diode barrier structure. For the study of photodiode properties, measurements were made of the current-voltage characteristics (VAC) in the dark and light modes. Measurements were made using a power source, a voltmeter and an ammeter. The limits of voltage measurements ranged from -2 V to 2 V to prevent possible breakdown of structures. A white LED with a power output of 30mW / cm2 was used as the light source. From the obtained CVCs it was obtained that a rectifying barrier is formed between the semiconductor films and the structure has a diode characteristic. The magnitude of the reverse current increases during illumination. Pressure was applied to the diode structures to investigate the piezoelectric effect. The pressure applied to the sample was changed by means of levers weighing 10, 20, 50, 100 and 200 grams. As a result of the measurements of the CVC during the application of pressure, it was found that the current on the forward and reverse branches of the CVC showed an increase in both the dark mode of measurement and in the light. This indicates the presence of a piezoelectric effect in this heterojunction. The calculated values of the sensitivity to pressure showed that the current on the back and forward branches of the CVC changes at different intervals. The highest sensitivity in the range 0–77.31 absolute units is observed for reverse current without illumination. With additional illumination, the sensitivity to the pressure on the back branch of the CVC decreases and is 0–7.73. All measurements made show the presence of a piezophototron effect, which allows the creation of new functional devices for measuring pressure and luminance based on this heterojunction.