Deposition of CdS Thin Film by Thermal Evaporation

Abstract

The CdS thin film is widely used for various

applications such as in solar cells, optoelectronic devices, LEDs,

photonics devices etc. The ultra-thin CdS layer is commonly used

as by layer or as window layer for CdTe, CIS, CIGS, CZTS thinfilm

solar cells. The CdS has high bandgap of 2.42 eV and

transparent after 510 nm wavelength. The excellent

optoelectronics properties of CdS material are very attractive as

hetero-junction partner (n-type) in thin-film solar cells. There are

several fabrication techniques used to deposit thin CdS layer such

as Screen Printing, Thermal Evaporation (TE), Molecular Beam

Epitaxy (MBE), Chemical Vapour Deposition (CVD), Pulsed

Laser Deposition (PLD), Sol-Gel, Spray Pyrolysis,

Electrochemical Deposition, Close Space Sublimation (CSS),

Sputtering, Chemical Bath Deposition (CBD) etc. Among them

TE is low cost, faster and the complete set-up is ready to be used

in the Lab. In this work, the CdS thin films were grown on

borosilicate glass substrate by thermal evaporation techniques

using VCM 600 V1 in a high vacuum condition at room

temperature. Around 200nm CdS thin film were fabricated on

BSG substrate and it took 35 minutes only. As grown CdS thin

film were characterized to evaluate its properties for the possible

application in CdS/CdTe thin-film solar cell. The as-deposited

CdS film characterization results showed lower resistivity with

higher mobility and carrier concentration which are good enough

to be used in thin-film solar cells, LEDs and photonic devices.