Electrical and optical measurements were used to characterize silicon-rich Si-Ge alloys up to 11.3% Ge content. Both high-resistivity p-type material, for use as p-i-n detectors for 1.06-μm radiation, and In-doped material, for use as an extrinsic IR detector beyond 8 μm, were studied. The measurement techniques include Hall-effect measurements versus temperature and photoresponse, photoconductivity, and absorption spectra. A major result is that multiple energy levels were found for acceptors. These energy levels arise from the interaction of the acceptor with its nearest-neighbor shell, and each level corresponds to a different number of Ge atoms in this shell. The concentration of acceptors having a given level corresponds to the probability of the nearest-neighbor shell having the corresponding number of Ge atoms; the probability of a Ge atom occupying a lattice site in the nearest-neighbor shell is from 0.5 to 1.0 times the probability of occupying a random lattice site. These results strongly affect the use of this material for extrinsic IR detectors because an extended response to long wavelengths results. We will also discuss the effects of the disorder in these materials on mobility and on spectral response and diffusion length measurements made on p-i-n detectors fabricated from these materials.© (1981) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

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Galvanomagnetic effects in semiconductors

Silicon-Rich Si-Ge Alloys For Infrared Detectors - Material Properties

The transverse magnetoresistance for nondegenerate semiconductors with the isotropic parabolic energy bands has been investigated for the case where acoustic phonons are the dominant scattering mechanism.1 It was shown that the transverse magnetoresistance increases with the magnetic field in the quantum limit. Some experimental results2 for the inelastic scattering mechanism showed that the transverse magnetoresistance depends strongly on the magnetic field. In this paper we calculate the transverse magnetoresistance of degenerate piezoelectric semiconductors like n-type InSb with isotropic parabolic energy bands throughout the strong-field region in which the splitting of Landau levels is much greater than the average carrier energy. In a crystal with low symmetry, the piezoelectric interaction may become important. This is the interaction between acoustic phonons and electrons through the polarization induced by the piezoelectricity of the crystal. Therefore we investigate the quantum effect of the transverse magnetoresistance for the inelastic scattering of acoustic phonons from the deformation-potential and piezoelectric couplings. The scattering is treated in the Born approximation for strong magnetic fields. We assume that the inelasticity is the dominant mechanism in resolving the divergence, and the cutoff energy due to the inelastic scattering does not change appreciably with the temperature.

Quantum effect on transverse magnetoresistance of degenerate piezoelectric semiconductors in strong magnetic fields

Transport phenomena are associated with the electric charge, heat, and mass flow in electrical and thermal conductivity and diffusion [14] They also include thermoelectric effects in crystals in the presence of electric potential and temperature gradients [15], and galvano-[61, 62] and thermomagnetic effects [111; 63; 64] which arise in crystals when an electric current or a heat flux passes through a crystal located in a magnetic field This chapter briefly considers all these effects

Transport Phenomena in Crystals

The current distribution in an isothermic isotropically conducting plate of circular form is investigated theoretically and experimentally, in the absence and in the presence of an external magnetic field that is perpendicular to the plate. The general solution of the Riemann-Hilbert boundary value problem has been obtained under these conditions. The analysis of this solution points to experimental possibilities of determining parameters of a crystal under consideration such as the specific electric conductivity (in the absence and in the presence of an external magnetic field), the mobility of current carriers in it, and others. All the basic results of the calculations undertaken were experimentally verified and quantitatively confirmed in a series of tests carried out on homogeneous monocrystalline n-germanium (with the specific resistivity of 1.1 ohm cm) at room temperature. It is known that investigations into the galvanomagnetic phenomena (longitudinal and transverse magneto-resistance, the usual, planar and longitudinal Hall effects and others) at the present time constitute not only a means of determining the characteristics of the parameters of the crystals in question (concentration of current carriers, their mobility, etc.) [1], but serve also as a proven and simple means of obtaining important information about the zone structure of crystals [2–5]. Such broadening of the circle of problems affecting the sphere of galvanomagnetic investigations already begins not to correspond to the established traditions of carrying out these investigations on test pieces of rectangular shape (as a rule, in the form of parallelepipeds). This lack of correspondence is greater due to a number of completely logical causes, certain requirements as to the geometrical dimensions of such test pieces (the ratio of length to width) [6] can far from always be satisfied. We note in this connection that in the study of galvanomagnetic phenomena in impulsive magnetic fields, for example, the use of test pieces of circular form would simplify the use of working volumes of small diameter. This, in the final analysis, is equivalent to broadening the scale of magnetic fields that can be used. The replacement of a rectangular plate by a circular disc enables us also to simplify a measurement of the parameters of semiconductor crystals which usually are obtained in circular form. Below we present theoretical and experimental investigations into the problem of measuring the galvanomagnetic effects in conducting crystals having a circular form.

The electric field in a circular semiconductor plate placed in a magnetic field

The effect of Landau level formation on the population of intrinsic electrons in InSb is probed near room temperature in magnetic fields upto 16 Tesla. Although the measured magnetic field dependence of the Hall coefficient is qualitatively similar to published results, it is shown that the data may also be explained by simply including ambipolar conduction. Thus the inference on band depopulation drawn from previous measurements on InSb is inconclusive unless both the Hall and the magnetoresistive components of the resistivity tensor are simultaneously measured and modelled. When the model includes both depopulation and ambipolar conduction, a reasonable agreement with theory can be established.

Galvanomagnetic effects in semiconductors

Citations

Silicon-Rich Si-Ge Alloys For Infrared Detectors - Material Properties

Quantum effect on transverse magnetoresistance of degenerate piezoelectric semiconductors in strong magnetic fields

Transport Phenomena in Crystals

The electric field in a circular semiconductor plate placed in a magnetic field

Magnetic field induced band depopulation in intrinsic InSb: A revisit

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