FEATURES STUDIES OF TRANSITION LAYERS IN SEMICONDUCTOR HETEROSYSTEMS

Studies of spectral characteristics in Schottky's contact specimens showed that photemf generated by mono­chromatic light, according to the formation mechanism, has a predominantly lateral nature, that is, in a hetero­system there are at least two areas separated by a potential barrier along the interface, with different conductivity levels. The feature of the photoemf spectral characteristics is a variations its appearance when changing the thermal annealing temperature of the studied heterosystems. A significant characteristic and a small amplitude of the characteristic indicates the formation of a transition layer, relatively homogeneous and with insignificant, compared with the volume of GaAs, the doping concentration. If the spectral characteristic has one maximum and amplitude, which several times exceeds the amplitude of a significant characteristic, which means the formation of a transition layer in the Schottky contact depletion area with high conductivity, compared with a quasine-neutral region of a semiconductor. The distribution of lateral photoemf along the sample also has a significant character. In order to obtain the correct results relative to the heterosystem transition layer, it is necessary to measure spectral acute characteristics at a distance from the point change sign of the emf that several times the diffusion length of non-equilibrium charge carriers in GaAs. The problem of the formation of a metal-semiconductor contact and other heterosystems accompanied by the occurrence of heterogeneous transition layers, always paid attention. The use of the proposed photovoltaic method allows to establish the degree of homogeneity of semiconductor layers, components of the structure and predict the redistribution of current density flowing through the physical scope of the device.

Photo-e.m.f. at a metal/layered n-InSe semiconductor contact under heating conditions of current carriers by an electric field

The features of the photo-e.m.f. are experimentally studied on the metal/n-InSe contact under conditions of heating the current carriers by an electric field in the temperature range of T0 =77÷350 K. The dependences of the photo-e.m.f. (Uph ) value have been measured in the absence of ( U p h 0 ) and under the condition of heating the current carriers ( U p h E ^ ) , as well as the value of Δ U p h = ( U p h E ^ -U p h 0 ) from the wavelength (λ) and light intensity (I), heating electric field strength (Ê), time (τ), temperature (T0 ), the initial value of the dark resistivity (ρD0 at 77K) n-InSe. It has been established that the heating of current carriers by an electric field significantly affects the magnitude and behavior of the photo-e.m.f. characteristics on the metal/n-InSe contact. The nature of this effect depends on T0,ρD0, I. The value of U p h E ^ significantly exceeds the value of U p h 0 . With an increase in Ê, the value of AUph increases linearly (ΔUph~Ê) at relatively small Ê, and the dependence of ΔUph (Ê) reaches saturation at higher Ê. The value of ΔUph decreases with increasing ρD0 , at relatively small Ê. With an increase in ρD0 , the relaxation time of the photo-e.m.f. also increases when turned off the pulse of the electric field. The obtained experimental results are explained on the basis of the dependence of the photo-e.m.f. on the metal/n-InSe contact on the effective temperature of heated current carriers (Te ), considering the effect of the spatial inhomogeneity of n-InSe crystals on the photo-e.m.f. and on the process of heating the current carriers.

INFLUENCE OF THE SEMICONDUCTOR CONDUCTIVITY ON THE VALUE OF THE SCHOTTKY BARRIER

В данной работе исследовано влияние проводимости полупроводника на Барьер Шотки в контакте металл полупроводник. В качестве объектов исследования выбраны контакты с алюминием следующих полупроводников: арсенида индия(InAs), арсенида галлия (GaAs)антимонида индия(InSb) и сульфида кадмия(CdS). Выбор этих кристаллов связан с тем, что ширина запрещенной зоны этих полупроводников возрастает от Еg = 0,18 эВ у арсенида индия до Еg = 2,53 эВ у сульфида кадмия, что соответствует поставленной задаче в данной работе. In this paper, the influence of the conductivity of a semiconductor on the Schottky Barrier in the metal-semiconductor contact is investigated. Contacts with aluminum of the following semiconductors were selected as objects of research: indium arsenide(InAs), gallium arsenide (GaAs), indium antimonide(InSb), and cadmium sulfide(CDs). The choice of these crystals is due to the fact that the band gap of these semiconductors increases from U = 0.18 eV for indium arsenide to U =eV for cadmium sulfide, which corresponds to the task in this paper.