Low-temperature thin film transistors based on pulsed laser deposited CdS active layers

Cadmium sulfide (CdS) thin films as n-type semiconductor material were deposited by pulsed laser deposition by varying the argon pressure at room temperature. The structural, morphological and stoichiometric characteristics of the CdS films were studied as a function of the deposition pressure. The results show that the argon deposition pressure had a dramatic impact on the CdS film properties. The CdS electrical resistivity increased 10 ⁴ times when argon pressure was increased from 8 to 10.66 Pa. These films were employed on fully-patterned thin film transistors (TFTs) fabricated by a photolithography-based process, and their electrical characteristics were measured. The TFTs electrical performance achieved a mobility of ∼24 cm ² /V-s with a threshold voltage from 1.5 to 12.6 V after testing. The deposition pressure of CdS for transistors fabrication, which optimizes the resulting electrical characteristics, was determined from this study.