Electronic structure and optical properties of CdTe rock‐salt high pressure phase

Abstract

This paper reports on optical absorption and reflectance measurements in thin CdTe samples up to 15 GPa. All studied samples become virtually opaque at the pressure transition between the zinc-blende and rock-salt phases (3.9 GPa). As pressure increases up to 10 GPa, a relative transparency region is observed between 1.2 eV and 2.4 eV, whose high energy edge shifts to higher photon energies. Above 10 GPa the transparency region gradually shrinks and disappears at about 11 GPa. The low energy side of the absorption spectrum is attributed to free carrier absorption, as electronic structure calculations show that rock-salt CdTe is a semimetal or a low gap semiconductor. Band filling effects lower the band-toband absorption coefficient and give rise to a "transparency" range, whose upper energy side is assigned to the direct transition at the Γ point, on the basis of its pressure coefficient. The shrinking and disappearance of the transparency region, along with a large increase of the reflectance in the mid infrared, is interpreted as the occurrence of a phase transition to the Cmcm metallic phase.

Structural and electronic properties of Pb1−xCdxTe and Pb1Bukała1, Sankowski2, Buczko3 et al. 2012Phys. Rev. B24560View full textAdd to dashboardCite

“…In the calculation performed in Ref. 36, RS-CdTe turned out to be a semimetal, in which the conduction band minimum at the X point would be nearly 2.5 eV below the valence band maximum located at Σ, midway the Γ -K line. This calculation, as well as another one presented in Ref.…”

“…Indeed, reflectance experiments in the mid-infrared do not indicate a metallic behavior of RS CdTe. 36 Güder et al after a careful analysis of the experimental results obtained for RS-CdTe at different pressures made an assumption that RS-CdTe is a narrow gap semiconductor, with the energy gap of few hundreds of meV at the Γ point. 36 This assumption is consistent also with results of Ref.…”

Structural and electronic properties of Pb1-xCdxTe and Pb1-xMnxTe ternary alloys

“…36 Güder et al after a careful analysis of the experimental results obtained for RS-CdTe at different pressures made an assumption that RS-CdTe is a narrow gap semiconductor, with the energy gap of few hundreds of meV at the Γ point. 36 This assumption is consistent also with results of Ref. 35. As described above, there are neither exact experimental data nor a reliable theoretically calculated band structure, to which we can fit our tight-binding parameters for RS CdTe bulk crystal.…”

Pressure-induced structural changes and elemental dissociation of cadmium and mercury chalcogenides

“…[1][2][3][4][5][6][7] The group IIB-VIA binary compounds have attracted signicant interest owing to their broad applications, such as light-emitting diodes, eld-effect transistors, chemical sensors, catalysis, and solar cells. [8][9][10][11] In addition, the high-pressure behaviour of group IIB-VIA binary compounds has been explored in the past 30 years. [12][13][14][15] By now, the generally accepted transition sequence for IIB-VIA compounds was zinc-blended (ZB) or wurtzite (WZ) / NaCl / Cmcm.…”