Photoluminescence spectra of InAs/GaAs QD structures have been studied at different pumping powers and temperatures. At low pumping levels, one of the spectral lines in an undoped sample is shifted as the power increases. As the temperature increases, the luminescence intensity in the high-energy portion of the spectrum decreases, and the low-energy spectrum is red-shifted. The presence of QDs of two characteristic sizes is demonstrated.

Specific features of photoluminescence of InAs/GaAs QD structures at different pumping levels

Secondary radiation (photoluminescence and Raman scattering) emitted by gallium phosphide single crystals at helium temperatures is investigated. It is established for the first time that, in the case when the secondary emission spectra are excited by a cw low-power He-Ne laser, whose linewidth lies in the transparency region of GaP, anti-Stokes photoluminescence from the bulk of the sample occurs due to interband and impurity recombination. The results obtained make it possible to carry out a qualitative and quantitative analysis of impurities which are present in the bulk of a semiconductor by recording the bulk anti-Stokes photoluminescence spectra at low temperatures.

Secondary anti-stokes emission from the bulk of gallium phosphide at 4.2 K

We have performed two experiments on the electron-hole liquid (EHL) in inhomogeneously stressed Ge in order to obtain information on the lifetime and radiative efficiency as a function of e-h pair density in the strain-confined electron-hole liquid (SCEHL). Our data can be explained if a density-independent recombination mechanism is the most important decay process, in contrast to unstressed Ge where it is small.

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Lifetime and radiative efficiency vs density in the strain-confined electron-hole liquid in Ge

Investigations of photoluminescence and Raman scattering in ternary Zn1–xMgxSe compounds at 4.2 K were performed both in the Stokes and anti-Stokes regions using the cw laser excitation with various wavelengths in the transparency band of the crystals. The anti-Stokes luminescence was observed for the first time in ternary Zn1–xMgxSe compounds. We suggest that the anti-Stokes emission is generated by the two-step excitation via deep-level centers. The low-temperature anti-Stokes photoluminescence is found to be a common property of the wide gap semiconductors and can probe the spatial distribution profiles of impurities in a volume of crystals.

Anti‐Stokes luminescence in ternary Zn1–xMgxSe compounds at liquid helium temperature

Submitted to International Conference on Recombination in Semiconductors, University of Southampton, U.K. 30 August - 1 September 1978 LBL-7368 LIFETIME AND RADIATIVE EFFICIENCY VS_ DENSITY IN THE STRAIN-CONFINED ELECTRON-HOLE LIQUID IN Ge Susan M. Kelso and John E. Furneaux —NOTICE r„„ April 1978 Prepared for the U. S. Department of Energy under Contract W-7405-ENG-48 BlSTKlBl'Tn/N Of ? HIS D0CXMENT 18 UNLIMITED

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LIFETIME AND RADIATIVE EFFICIENCY VS DENSITY IN THE STRAIN-CONFINED ELECTRON-HOLE LIQUID IN Ge

Kinetics and magnetic-field investigations of photoluminescent spectra at temperatures between 0.5 and 4.2K in moderately heavily doped Ge:Sb (n D ∼ 10 16 -10 17 cm -3 , below the Mott transition n c = 10 17 cm -3 ) revealed strong changes in the phase diagram of non-equilibrium current carriers compared to the case of pure or lightly doped Ge. The data show that due to the presence of narrow impurity bands at such doping concentrations the non-equilibrium impurity-band current carriers (D-) and free holes (h) condense into the D-H liquid surrounded by the gas phase of D - H-plasma.

V. A. Fradkov

Papers

Photoluminescent discovery of the impurity–band non-equilibrium current carriers condensation in Ge : Sb

Spectral dependent kinetics of the EHD luminescence in As-doped Ge