Sub‐Band Gap Absorption in As‐Deposited and Annealed nc‐CdSe Thin Films Using Constant Photocurrent Method (CPM)

摘要

Nanocrystalline CdSe thin films have been prepared by thermal vaccum evaporation technique using Inert Gas Condensation method using Argon as inert gas. XRD confirms the crystalline cubic nature of nc‐CdSe thin films. The optical band gap is calculated for as deposited nc‐CdSe and it comes out to be 2.1 eV. CPM has been used to measure sub‐band gap absorption in nanocrystalline CdSe thin films. The thin films of nc‐CdSe have been annealed at 80?°C for one hour and sub‐bandgap absorption in annealed samples has also been calculated. Slope of Urbach tail which is a measure of disorder in both as deposited and annealed samples has been calculated. In the case of as deposited nc‐CdSe thin films, Urbach slope is 354 meV. It decreases to the value 198 meV after annealing which shows structural disorder decreases after annealing.