Optical absorption of zinc selenide doped with cobalt (Zn_1−xCo_xSe) under hydrostatic pressure

Abstract

The optical absorption of the diluted magnetic semiconductor Zn_1−xCO_xSe (x = 0.02) has been measured at room temperature under hydrostatic pressure up to 14GPa in a membrane diamond-anvil cell. We found two absorption features: (i) an absorption structure in the energy range 1.6−1.8eV, with a negligible pressure shift (i.e., 0.45 ± 0.05 meV/GPa) which we have identified as the Co²⁺(3d⁷) internal transition ⁴A₂(F)→+⁴T₁(P) and (ii) an onset in the energy range 2−2.7eV which redshifts with pressure (−8.1±0.6meV/GPa). We have attributed such absorption edge to charge transfer between the ZnSe valence band and the Co²⁺(3d⁷) levels.

Key Words:

• Optical absorption
• ZnSe
• diluted magnetic semiconductors
• hydrostatic pressure