Structural and optical characterization of undoped and indium-doped CdS films grown by pulsed laser deposition

Photoluminescence of N‐Type CDS Thin Films

“…As mentioned before, the narrow peak at 2.518 eV near to the band edge region: in the undoped CdS film is due to excitonic recombination. The broader PL bands at approximately 2.50 eV and 2.48 eV in the CdS:In (1%) and CdS:In (5%), respectively, are attributed to free electron-hole pairs recombinations [7]. In this figure it is also noticed that the peaks became wider with doping and the positions of the peaks are also shifted towards lower energy with doping.…”

“…It consists of two prominent broad bands approximately 2.3 eV (green emission) and 1.6 eV (red emission). Also Figure 3a displays the PL spectra of CdS thin films prepared by pulsed laser deposition technique grown on quartz substrates by Perna et al [7]. For undoped CdS film they observed an emission at 2.518 eV which is due to excitonic recombination, and a broad PL band at approximately 2.0 eV which is attributed to radiative recombination involving impurity and/or defect levels.…”

“…Different dopants can be used to produce n-type CdS thin films such as In [3,7,13], B [11], Ag [7]. In the case of n-type materials, doping is known to create donor levels in the bandgap.…”

“…The decrease in the intensity of the red emission with boron concentration according to them was caused by the decreasing of the density of surface Cd-vacancies, because of filling boron atoms. For undoped and indium doped CdS thin films prepared by pulsed laser deposition technique grown on the quartz substrates Perna et al [7] measured the PL spectra at different temperatures ( Figure 3). As mentioned before, the narrow peak at 2.518 eV near to the band edge region: in the undoped CdS film is due to excitonic recombination.…”

“…Thin films of n-type CdS are widely used as a window layer in heterojunction solar cells such as CdS/CdTe solar cells. Doped and undoped CdS thin films can be obtained by different techniques such as; spray pyrolysis (SP) [3], chemical bath deposition (CBD) [2,4], pulsed laser deposition [5,6,7], laser ablation [1], thermal evaporation [8].…”