Structural characterizations and optical properties of InSe and InSe:Ag semiconductors grown by Bridgman/Stockbarger technique

Abstract Undoped InSe and Ag doped InSe (InSe:Ag) single crystals have been grown by using the Bridgman/Stockbarger method. The freshly cleaved crystals have mirror-like surfaces even without using mechanical treatment. The structure and lattice parameters of the undoped InSe and InSe:Ag semiconductors have been analyzed using a X-ray diffractometer (XRD), Scanning electron microscopy (SEM) and energy dispersive X-rays (EDX) techniques. It is found that the InSe and InSe:Ag crystals had hexagonal structure, and calculated lattice constants were found to be a =4.002 A and c =17.160 A for InSe and a =4.619 A and c =17.003 A for InSe:Ag. The crystallite sizes have been calculated to be 40–150 nm for InSe and 75–120 nm for InSe:Ag from the SEM results. Ag doping causes a significant increase in the XRD peak intensity. It has been observed from EDX results that InSe contains In=57.12%, Se=38.08% and O=4.81%, respectively. Absorption measurements have been carried out in InSe and InSe:Ag samples in the temperature range 10–320 K with a step of 10 K. The first exciton energies for n =1 were calculated as 1.328, 1.260 eV in InSe and were 1.340, 1.282 eV in InSe:Ag at 10 K and 320 K, respectively.