Ves S., Strossner K., Christensen N.E., Chul Koo Kim, Cardona M.
The variation of the lowest direct absorption edge (e0) of ZnSe with hydrostatic pressure has been measured at room temperature with a diamond anvil cell for pressures up to the phase transition (13.5+or-0.2 GPa). The gap varies sublinearly with pressure. However, when the gap is plotted as a function of the relative change of the lattice constant (- Delta a/a0) it shows a slight supralinearity in contrast to most III-V tetrahedral semiconductors which retain a slight sublinearity even as a function of (- Delta a/a0). The experimental results are compared to theoretical calculations based (a) on the local density approximation combined with the self-consistent band calculations using the MTO method (LD-LMTO) and (b) on a local empirical pseudopotential. Both calculations predict a sublinear dependence of E0 as a function of (- Delta a/a0). The semiempirical Murnaghan's equation of state that was calculated with the LD-LMTO method, has also been tested by determining the lattice constant under pressure with an energy dispersive X-ray diffractometer.
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