spinsis clearly impossible. ) It appears that just as long-range ferromagnetic interactions are good for classical methods, long-range oscillatory interactions lead to these Quctuations and are bad for classical or semiclassical methods applied for small spins.We have examined the Anderson spin-wave theory of antiferromagnetism'4'~which is patently correct in case (a) (although it is not mathematically exact).However, in spin-wave stable systems the approximate antiferromagnetic eigenstate has in general a complex energy and is, therefore, unstable, even in such a favorable model as we have considered, where nearest neighbor bonds are antiferromagnetic, and the lattice is three-dimensional simple cubic.ported. 4' The electrical measurements of the n-type

We have examined band-edge fluorescent emission spectra in various II-VI compounds at 4°K with the objective of establishing correlations between the presence of specific spectra and the presence of specific defects. The basis for such correlations is the proven existence of radiative recombination from excitons bound to defects, 1 " 3 and the expectation that such mechanisms can account for much of the plethora of band-edge spectra observed. We have found evidence for a simple relationship governing such correlations for this family of compounds-a significant extension of Haynes's observations 1 in silicon. Figure 1 (insert) illustrates the procedure employed for acceptor defects. We have attempted, by purification and subsequent introduction of acceptor defects, to obtain samples which exhibit a dominant emission process of near-band-gap energy at 4°K correlated with the presence of a dominant emission process 0.200 0,050 0010 0005 0002,

Single crystals of ZnSe have been prepared by the vapor growth technique and optical and electrical measurements on these crystals are reported. Analysis of the reststrahlen reflection peak gives 0.026 ev for the transverse optical phonon energy. The longitudinal optical phonon energy is 0.031 ev as calculated from the transverse phonon energy, the static dielectric constant, ε0=8.1±0.3, and the high-frequency dielectric constant, ε∞=5.75±0.1. The effective ionic charge calculated from the Szigetti formula is 0.7±0.1. Exciton absorption peaks associated with the valence and conduction bands in the vicinity of Γ were observed at liquid hydrogen temperature with the principal peak at 2.81±0.01 ev. The exciton reduced mass 0.1 m0 combined with the room temperature electron-to-hole mobility ratio of 12, obtained by preliminary transport measurements on n- and p-type ZnSe gives tentative values of 0.1 m0 and 0.6 m0 for the electron and hole masses, respectively. Reflectance was determined by various methods in the range 0.025 to 14.5 ev photon energy and was analyzed by the Kronig-Kramers inversion method to obtain the optical constants in the 1 to 10 ev range. A number of peaks appear in the imaginary part of the dielectric constant. The first set of peaks, 2.7 and 3.15 ev, are believed to be due to exciton and interband transitions at Γ with a spin-orbit valence band splitting of 0.45 ev. The second set of peaks, 4.75 and 5.1 ev, are tentatively assigned to transitions at L with a spin-orbit splitting of 0.35 ev. Other peaks are observed at higher energies.

No abstract

The diffusivity and solubility of Cu in CdTe has been measured between 97° and 300°C using radiotracer techniques. The system studied involved chemically formed Cu2Te films on undoped zone-purified CdTe single crystals. The solubility was found to vary from approximately 3×1016 to 2×1018 cm−3 in the temperature range studied. The diffusivity corresponding to these solubilities is given by D(cm2·sec−1) =3.7× 10−4 exp (−0.67 eV/kT). A much faster diffusing ``tail'' involving about 1015 cm−3 Cu is also observed.