P-type CuxS thin films: Integration in a thin film transistor structure

Nunes de Carvalho, C., Parreira, P. , Lavareda, G., Brogueira, P. and Amaral, A. (2013) P-type CuxS thin films: Integration in a thin film transistor structure. Thin Solid Films, 543, pp. 3-6. (doi:10.1016/j.tsf.2013.03.141)

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Abstract

CuxS thin films, 80 nm thick, are deposited by vacuum thermal evaporation of sulfur-rich powder mixture, Cu2S:S (50:50 wt.%) with no intentional heating of the substrate. The process of deposition occurs at very low deposition rates (0.1–0.3 nm/s) to avoid the formation of Cu or S-rich films. The evolution of CuxS films surface properties (morphology/roughness) under post deposition mild annealing in air at 270 °C and their integration in a thin film transistor (TFT) are the main objectives of this study. Accordingly, Scanning Electron Microscopy studies show CuxS films with different surface morphologies, depending on the post deposition annealing conditions. For the shortest annealing time, the CuxS films look to be constructed of grains with large dimension at the surface (approximately 100 nm) and consequently, irregular shape. For the longest annealing time, films with a fine-grained surface are found, with some randomly distributed large particles bound to this fine-grained surface. Atomic Force Microscopy results indicate an increase of the root-mean-square roughness of CuxS surface with annealing time, from 13.6 up to 37.4 nm, for 255 and 345 s, respectively. The preliminary integration of CuxS films in a TFT bottom-gate type structure allowed the study of the feasibility and compatibility of this material with the remaining stages of a TFT fabrication as well as the determination of the p-type characteristic of the CuxS material.

Item Type:Articles (Letter)
Additional Information:This work was financially supported by the PTDC/EEA-ELC/74334/2006 and PTDC/EEA-ELC/108882/2008 projects.
Keywords:P-type materials, P-type thin films, copper sulphide, TFT, thin film transistor, CuS, CuxS.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Parreira, Dr Pedro Miguel
Authors: Nunes de Carvalho, C., Parreira, P., Lavareda, G., Brogueira, P., and Amaral, A.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Thin Solid Films
Publisher:Elsevier
ISSN:0040-6090
Published Online:03 July 2013

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