Influence of electrical field on the optical absorption in InSe:Er crystals

InSe:Er single crystal was grown by using the Stockbarger method. The growthed InSe:Er single crystal ingots were 12 mm in diameter and about 80 mm in length. The absorption measurements were carried out for U=0 and U=40 V states of InSe:Er sample in the temperature range of 10-320 K. Binding energies for U=0 and U=40 V states were calculated to be (4.25±0.04) and (3.25±0.04) MeV respectively. At 10 K, direct band gaps of U=0 and U=40 V states of InSe:Er are 1.322 and 1.315 eV and indirect band gaps are 1.313 and 1.308 eV, respectively. The steepness parameters and Urbach energy for the U=0 and U=40 V states in InSe:Er sample increased with increasing sample temperature in the range 10-320 K