Resistivity and subsurface damage of linear scratches in p-ZnTe

Abstract

Resistivity measurements across a linear scratch on (110) p-type ZnTe samples with resistivities at different room temperatures have been made using the four-point probe method. The scratches are made on samples maintained at elevated isothermal temperatures ranging from 100–650 K by a Vickers Pyramid Diamond with a dead load of 2 N. The measurements show that the relative change in resistivity (RCR) increases with temperature up to an optimum temperature, after which the resistivity decreases, crosses zero and changes its sign. The temperature at which the maximum RCR occurs is 425 and 450 K in samples with resistivity 0.982 and 1.530 Ω cm respectively and around 470 K in samples with resistivities of 2.873, 3.401 and 5.215 Ω cm. The temperature at which the RCR becomes zero is found to increase with an increase in the initial resistivity of the sample. An analysis of the four-point probe geometry showed that the voltage across the scratch, before attaining the maximum RCR, increases due to an increase in the size and resistivity of the subsurface damage and later it decreases as the damage size approaches saturation. The formation of microcracks during the scratching process is discussed.