https://doi.org/10.15407/iopt.2019.54.134
Optoelectron. Semicond. Tech. 54, 134-138 (2019)
Ya.М. Olikh1, M.D. Tymochko1, O.Ya. Olikh2
1V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine
2Taras Shevchenko National University of Kyiv
Acoustic-induced temperature peculiarities of electrical conductivity in CdZnTe:Cl due to metastable DX centers
In low-resist crystals Cd0.96Zn0.04Te:Cl (NCl≈5·1024 m-3) the peculiarities of the ultrasound (US) influence on the temperature characteristics (77÷300) К of electrical conductivity σ(Т) were revealed, which were determined not only by temperature but also the direction of its change. Thus σ(Т) depends on the previous state of the sample – from the direction of temperature change, or in the process of heating or cooling. We observe the following: а) hysteresis σ(Т) without of US does not appear; б) the maximum acoustic-indused changes σ(Т) are observed at temperatures (100÷200) К. In the process of the sample heating, after the pre-cooling, the value of the acoustic-indused changes σ(Т) is ~2 times greater than for the cooling. A separate comparison of the acoustical-indused electron concentration and their mobility magnitude, which are received from independent Hall measurements. In order to understand what processes occur in our case, we have carried out additional theoretical approximations such as the method of differential evolution of experimental concentration and mobility curves n(Т) and µ(Т). It allowed to establish that the determining contribution to the hysteresis effect σ(Т) is acoustic-indused residual growth of the electron concentration. To clarify the mechanism of the US action at μHexp(Т), it is important to estimate the relative contribution of each scattering mechanisms of carriers (on the neutral impurities, dislocations, ionized impurities and lattice) and their changes under US.
We believe that hysteresis in CdZnTe crystals caused by ultrasound is explained by composite defect complexes, due to the presence of zinc (possibly complexes [(VZn2-2ClTe+)0] і [(VZn2-ClTe+)-]), because hysteresis is not observed in CdTe crystals. In particular, such defects can be DX centers, which under the action of ultrasonic loading can go into a metastable state.
Keywords: ultrasound, CdZnTe single crystals, point defects, dislocation clusters, Hall effect.
