Resonant Raman Scattering near El + dl in Cd,Hgl-,Se BY K . KUMAZAKIRaman scattering by phonons is measured in Cd,Hgl -,$e with 5 = 0 to 0.3 on (loo), (110) and (111) surfaces near the El + A, energy gap a t room temperature. From these measurements, the composition dependence of the HgSe-like TO and LO mode frequencies is obtained. The plasmon-LO phonon coupled modes and a cluster mode are also observed. Effective high-frequency dielectric constants calculated by the extended Lyddane-Sachs-Teller relation show a discontinuity near the semimetal-semiconductor transition point. This discontinuity is attributed to the contribution of interband terms to the dielectric function. The results obtained from the Raman measurements are compared with those from far-infrared measurements. Raman-Streuung durch

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These results suggest that the new method can be used to diagnose the cirrhotic liver objectively.

Recently Phillips (1) has succeeded in describing the close relationships between bonding properties and band structures in semiconductors by using the new ionicity scale f. (2 to 4). Martin (5,6) found that the elastic properties of zincblende structure crystals could approximate simple analytic functions of f.. Although the band structures of HgSe were frequently reported by many workers (7), we just knew a part of the defect structures (8, 9) of it. Especially there a r e few detailed data (10, 11) on the elastic properties in HgSe. In this note we report the relations between the elastic properties of HgSe and the ionicity fi and make discovery of the bonding forces of mercury chalcogenides ((3 -He, HgSe, and HgTe). 1 1The velocities of HgSe were measured by the modified ultrasonic pulse-echooverlap method (12). The temperature dependences of the elastic constants a r e calculated from the measured velocities over the temperature range of 77 to 350 K a s shown in Fig. 1. The low temperature values (T--0 K) of the elastic constants a r e determined to be Cll = 6.90, C12 = 5.19, and C from Fig. 1. 11 2 = 2.33 in units of 10 dyn/cm 44 Martin (5, 6) made clear that all atomic forces in the tetrahedrally coordinated crystals were described well by the bond-stretching force a and bond-bending force P , including the effects of Coulomb forces and internal strains a s follows:(2) C44 = ( a + 0)/4,a -0.14s -ct;" , (3) C = ( a + p ) / 4 a -0.27s ,and Coulomb force s and the internal strain parameter 5 a r e defined by 2 4 s = (e*) / & d ,

Hall coefficients and electron conductivities of HgSe crystals annealed in a broad range of Hg and Se vapour pressures are measured at room and liquid nitrogen temperatures. The dominant point defects in HgSe are Hg interstitials and Se and Hg vacancies. Formation enthalpies of these defects are estimated by thermodynamical analysis and are compared with other II‐VI compounds. (P‐T‐x) diagram and existence region are obtained by the present annealing experiments. The electron concentration is expressed in terms of the gas pressure and the treatment temperature.