Solomon Zwerdling

Oscillatory magneto-absorption in gallium antimonide JA-1149∗☆

Abstract High-resolution magneto-absorption measurements made at photon energies just above the intrinsic absorption edge in GaSb have revealed an oscillatory spectrum having a strong resemblance to the corresponding spectrum for direct transitions in germanium. Eight successive transmission minima were observed in magnetic fields up to 38.9 kG at both 1.5 and 4.2°K, using polarized incident radiation. The value of the energy gap found is g = 0.813±0.001 eV and is shown to be attributable to direct transitions of electrons between the valence and conduction bands. The electron effective mass, m∗ = (0.047 ± 0.003)m0, was determined by considering transitions from the heavy holes to the conduction band and employing the data of the E||B spectrum. The existence of fine structure, although not resolved, is indicated by the unsymmetrical character of some of the transmission minima. The first absorption line is believed to contain exciton absorption. The inability to resolve the fine structure and exciton absorption is attributed to line broadening and overlapping due chiefly to scattering by the high impurity density in the sample.

Oscillatory Magnetoabsorption in InSb Under High Resolution

Polarized oscillatory magnetoabsorption spectra of exciton formation transitions in InSb have been measured under high resolution at liquid helium temperature. An unstrained high‐mobility sample 5 μ thick and magnetic fields up to 39.1 kgauss were used. Diffraction grating dispersion for the region 3.7<λ<6.0 μ made possible a resolution of 1−7×10−4 ev and the determination of absorption maxima to ±5×10−5 ev. Sixteen minima were resolved with E⊥B for a field of only 5.0 kgauss. The initial interpretation of the detailed spectra obtained involved fitting theoretical spectra calculated from the theories of Kane, Luttinger, and Elliott‐Loudon in order to account for band nonparabolicities, valence band degeneracy effects, and exciton binding energies, respectively. The results experimentally established the light‐hole nonparabolicity, the valence band degeneracy effects for low magnetic quantum numbers, and the existence of high‐field excitons in InSb.

Quantum magneto-absorption phenomena in semiconductors

Abstract The existence of quantized magnetic or Landau levels in a semiconductor in a magnetic field can give rise to a variety of magneto-absorption phenomena. The oscillatory magneto-absorption of the direct transition has been observed in germanium, indium arsenide and indium antimonide.

Calibration of prism spectrometers in the ultraviolet, visible and near-infrared regions

Emission line spectra of the elements Hg, Cd, Zn, He, Ne and Rb were used in the development of a precise and comprehensive calibration procedure for the fused silica and DF-2 glass prisms covering the range 0.194 μ < λ< 2.33 μ and 0.365 μ < λ < 2.33 μ, respectively. Spectrograms of the emission lines are presented together with experimental conditions necessary to reproduce them, the photon energy and vacuum wavelength of each identified line, as well as other pertinent information. Since the emission lines are very narrow and their wavelength values are accurately known, the precision of the method is determined only by the experimental uncertainty in obtaining the corresponding spectrometer drum readings. Data are reported for 233 lines observed with the fused silica prism and for 341 lines with the DF-2 glass prism. The observations were made with a Perkin-Elmer Model 13-U single-pass spectrometer using Osram spectral lamps. The detectors used were the RCA photomultiplier type 7200 for the ultraviolet and visible regions, the type 1P21 for the visible region (in which it has a better SN ratio than the 7200), and the PbS photoconductive detector for the near infrared. A discussion of experimental aspects is presented including details on spectrometer arrangements and problems of technique. In addition, a procedure was developed to provide a definitive and precise method for plotting the final calibration curves in terms of photon energy versus spectrometer drum reading, based on a modification and extension of the empirical relationship of McKinney and Friedel. A detailed description of the adaptation and the application of this procedure is given, together with the modified equation and typical values of its constants pertinent to each prism.