PHOTOELECTRIC PROPERTIES OF MnIn2S4 SINGLE CRYSTALS

The spectral distribution of the photoconductivity and the temperature dependence of the photocurrent of MnIn2S4 single crystals are investigated. The intrinsic, impurity photoconductivity and a maximum at an energy of 2.69 eV, which is associated with the intracenter transition of Mn2+ ions (6A1→4A1), are revealed in the photoconductivity spectrum. The region of the wavelengths of 600–1000 nm appears with an excess of manganese in the crystals and is caused by a donor defect. At temperatures of 80—145 K, the increase in the photocurrent is associated with the thermal depletion of the adhesion levels. The activation energy of the adhesion levels is determined.

Induced electronic phenomena in crystals of p-GaSe semiconductor promising for optoelectronics

An induced impurity photoconductivity by the electric field, thermally stimulated conductivity and spontaneous pulsations of the dark current were found in the undoped (with a dark resistivity P77≈3•104÷108 Ω-cm at T≈77 K) and erbium doped (NEr=10–5÷10–1 at.%) p-GaSe crystals in the temperature range of T≤240÷250 K at electric field strengths (E) creating a noticeable injection. It was found that the value of the observed impurity photoconductivity (M) monotonically increase at low illumination in undoped crystals with increasing P77 and its spectrum smoothly expands towards longer waves. The value of ∆ii and the width of its spectrum change non-monotonically with increasing NEr in doped crystal and it gets its maximum value at NEr ≈5•10-4 at.%. The intensity of spontaneous pulsations increases with increasing E at the higher electric field strengths. However, the impurity photoconductivity and the peak of thermally stimulated conductivity gradually disappeared. The amplitude and frequency of the observed spontaneous pulsations of the dark current is increased with increasing in the injection ability of the contacts. Moreover, the pulsations of the dark current gradually disappeared with increasing T. It was shown that all these three phenomena are directly caused by the recharge of sticking levels with a depth Er ≈+0.42 eV and a density Nt≈ 1015 cm-3 by injected holes. However, in high-resistance undoped and doped Er ≤10-2 at.% crystals, it is also necessary to consider the presence of random macroscopic defects in the samples to explain their features. A qualitative explanation is proposed based on the obtained results.

Influence of γ – radiation on the properties of silicon with clusters impurity atoms of manganese and nickel

In works [1-4], it was shown that a number of new physical phenomena are observed in silicon with nanoclusters, such as high-temperature negative magnetoresistance (NMR), anomalously high impurity photoconductivity, giant residual photoconductivity, etc. All these phenomena are directly related to the presence of multiply charged, magnetic clusters of manganese atoms in the silicon lattice. It is shown that, on the basis of such materials, it is possible to create fundamentally new, highly sensitive magnetosensors, photodetectors of infrared radiation operating in the μm region and photomagnetic devices.