Особливостi протiкання струму при ультразвуковому навантаженнi в сильно компенсованих низькоомних кристалах CdTe:Cl

• Дата: 2019
• Автори: Olikh, Ya. M., Tymochko, M. D.
• Формат: Стаття
• Мова: English; Ukrainian
• Опубліковано: Publishing house "Academperiodika" 2019
• Теми: ультразвук; дислокацiї; монокристали CdTe; ефект Холла; релаксацiя електропровiдностi; ultrasound; dislocations; CdTe single crystals; Hall effect; conductivity relaxation; -
• Онлайн доступ: https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2019082
• Назва журналу: Ukrainian Journal of Physics

To elucidate the mechanism of influence of ultrasound on the temperature, T, dependence of conductivity (q(T)) in low-resistance CdTe:Cl (NCl ≈ 1024 m−3) single crystals of the n-type, the Hall effect and the relaxation kinetics of q(t) at the ultrasound (fUS ∼ 10 MHz, WUS ∼ 104 W/m2) switching-on and -off have been studied in a temperature interval from 77 to 300 K. A completely reversible dynamical influence of ultrasound is revealed for the first time. It has different characters for the low (LT, T < 180 K) and high (HT, T > 200 K) temperature intervals. Acoustically stimulated changes in the HT region are found to be in-significant: the mobility of charge carriers decreases a little, and long-term processes of q(t) relaxation are not observed. In the LT region, the relative acoustically stimulated changes grow; in particular, the duration of q(t) relaxation processes increases, and they reveal a two-stage character. To explain this phenomenon, the model of a heterogeneous semiconductor containing clusters of impurity defects in vicinities of dislocations is applied. A mechanism is proposed that relates the “instant” increase of q(t) with the acoustically stimulated reduction of the amplitude of fluctuations of the large-scale potential owing to the enlargement of the effective electronic radius of dislocation impurity clusters. Long-term (50–500 s) temperature-dependent relaxation processes are governed by the diffusive reconstruction of the point-defect structure in the cluster bulk, including the transformation of acceptor (V2−CdCl+Te)− complexes into neutral (V2−Cd2Cl+Te)0 ones.