BANDGAP OF ZN1-XMNXTE - NONLINEAR DEPENDENCE ON COMPOSITION AND TEMPERATURE

Reflectance spectroscopy experiments have been carried out to investig ate the behaviour of the fundamental transition of Zn1-xMnxTe as a fun ction of Mn mole taction x and temperature: E(g) = f(x, T). For the fi rst time a nonlinear composition dependence is reported. The overall c omposition dependence can be approximated by two linear functions for the concentration ranges 0 less-than-or-equal-to x less-than-or-equal- to 0.1 and x > 0.1, respectively. This bandgap anomaly can be explaine d within the framework of exchange interaction. The temperature depend ence for small amounts of manganese can be approximated satisfactorily by Varshni's formula, but for manganese concentrations x > 0.1 an add itional blue shift of E(g) is observed.