Effective mass calculation for InSe, InSe:Er crystals

Undoped indium selenide (InSe) and Er doped InSe single crystals were grown by Bridgman–Stockberger method. The InSe crystals both undoped and doped Er had no cracks or voids on the surface. No polishing or cleaning treatments were carried out on the cleaved faces of these samples because of the natural mirror-like cleavage faces. The absorption measurements were carried out in the temperature range 10–320 K and the external electric field effect on the absorption measurements is investigated. The absorption edge shifted towards to the longer wavelengths under an electric field as 6 kV/cm. Using the electric field shifting, effective mass values are calculated.