Search

High-resistance Pb1 –xSnxTe〈In〉 layers grown by molecular beam epitaxy on BaF2(111) substrates with compositions close to band inversion have been investigated. The I–V characteristics and relaxation dependences of the photocurrent of the structures in dependence on the chemical surface treatment and subsequent exposure of the samples in air have been examined. It has been observed that the characteristics significantly transform depending on the physicochemical surface state. It has been found that the chemical surface treatment in the hydrochloric acid solution in isopropyl alcohol leads to an increase in the current by up to four orders of magnitude with the subsequent recovery of the I–V characteristics upon exposure of the samples in air for several days.

This paper reports a study of the current–voltage (I–V) features of the p-i-p structures based on Pb1–xSnxTe:In films with the tin content х ≈ 0.31 in which the metal–insulator transition occurs. It is shown that the photocurrent is the hole current under light interband excitation, and electron trapping is dominant. The experimental and theoretical data are compared.

The flowing of the injection current in Pb1 − xSnxTe:In structures (x ≥ 0.3) with various metal contacts at the temperature of helium is considered. The current-voltage characteristics (CVCs) of the structures in the dark and when they are illuminated from the blackbody model are given. It is found that the CVCs depend on the materials of the metal contact. The localized state density distribution over the forbidden band in structures with various contacts is given and the influence of the contact region and localized states on the CVC is discussed. The problems of constructing photodetectors with optimum threshold characteristics are discussed.

Photoelectric properties of Pb1 − xSnxTe:In films with composition x > 0.3 in the temperature range from 4.2 to 80 K have been investigated. High sample sensitivity to black-body radiation has been discovered at the temperature of helium, and as the temperature of the radiation source decreases the sensitivity increases, which can be connected with the optical-frequency transition in the short-wavelength infrared and terahertz spectral range. The detectivity value D* = 8.2 × 1016 cm · Hz1/2/W corresponding to the NEP = 3.1 × 10−18 W/Hz1/2, has been obtained at detector temperature 4.2 K and TBBR = 15 K.

Damping oscillations of a current are found in the PbSTe:In films after supplying a direct voltage to them in the absence of background illumination. A nonmonotonic transition to the steady state is discussed in the scope of the theory of the currents confined by a space charge upon the capture of electrons injected from the contacts to the traps distributed by energy, which leads to oscillating variation in polarizability and injection current. The ratio of the total current under the excitation by laser radiation with wavelength λ = 205 μm (hν = 0.006 eV) to the dark current could be larger or smaller than unity depending on the injection level of the electrons, i.e., supplied voltage, which can be interpreted in the scope of the suggested model.

Under non-illumination conditions, dying oscillations of electric current in PbSnTe:In film structures were observed upon applying a constant voltage to the samples. A model for the transition of the structures to a stationary state is discussed, in which capture of electrons injected out of contacts at energy-distributed traps is assumed; this capture leads to non-monotonic variation of polarizability and injection current in PbSnTe:In.

It is of practical importance to study the temperature sensitivity as the fractional change of the surface acoustic wave (SAW) characteristics due to the substrate temperature variations. So, the temperature coefficient of the delay time (TCD) is a major consideration for the selection of the substrate material in the design either of stable SAW-oscillators or temperature sensors [1–2].