Electrical behavior of p-type PbS-based metal-oxide-semiconductor thin film transistors

• DOI: 10.1016/j.tsf.2010.08.092
• Publication Date: 2010-08-22T08:28:54Z
• Authors: I.E. Morales-Fern...; M.I. Medina-Montes; L.A. González; B. Gnade; M.A. Quevedo-López; R. Ramírez-Bon
• Keywords: Nanocrystalline material; Electron Mobility

Abstract Chemically deposited lead sulfide (PbS) thin films were used as the semiconductor active layer in common-gated thin film transistors. The PbS films were deposited at room temperature on SiO 2 /Si-p wafers. Lift-off was used to define source and drain contacts (gold, Au) on top of the PbS layer with channel lengths ranging from 10 to 80 μm. The Si-p wafer with a back chromium-gold contact served as the common gate for the transistors. Experimental results show that as-deposited PbS are p-type in character and the devices exhibit typical drain current versus source–drain voltage ( I DS – V DS ) behavior as a function of gate voltage. The values of threshold voltage of the devices were in the range from −7.8 to 1.0 V, depending on the channel length. Channel mobility was approximately 10 − 4 cm 2 V − 1 s − 1 . The low channel mobility in the devices is attributed to the influence of the microstructure of the nanocrystalline thin films. The electrical performance of the PbS-based devices was improved by thermal annealing the devices in forming gas at 250 °C. In particular, channel mobility increased and threshold voltage decreased as a consequence of the thermal annealing.