OPTICAL PROPERTIES OF Ge2Sb2Te5 COMPOUND

Abstract

Ge2Sb2Te5 (GST225) compound has two main phases: amorphous and crystalline. In crystalline state, there are two types of lattice structure: fcc face-center-cube (crystallized at temperature of 1500C). The optical constants (n, k, α) of GST225 depend on the wavelength. There are differences of these optical constants between amorphous and crystalline states. This difference is called optical contrast. The very important parameter for the GST225 is the band gap (Eg). For GST225 band gap Eg is from 0.61 eV to 0.64 eV in amorphous state and 0.4 eV in crystalline state.