A conduction model for semiconductor-grain-boundary-semiconductor barriers in polycrystalline-silicon films

• Published in: IEEE transactions on electron devices Vol. 30; no. 2; pp. 137 - 149
• Main Authors: Lu, N.C.-C., Gerzberg, L., Chih-Yuan Lu, Meindl, J.D.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.02.1983; Institute of Electrical and Electronics Engineers
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic transport in condensed matter; Exact sciences and technology; Physics; Temperature; Electrical conductivity; Semiconductor materials; Voltage current curve; Impurity density; Charge carrier mobility; Polycrystal; Space charge; Theoretical study; Hall effect; Experimental study; Thin film; Grain boundary; Transport process; Charge carrier scattering; Models; Silicon
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/T-ED.1983.21087

A quantitative trapping model is introduced to describe the electrical properties of a semiconductor-grain-boundary-semiconductor (SGBS) barrier in polysilicon films over a wide temperature range. The grain-boundary scattering effects on carrier transport are studied analytically by examining the behavior of the height and width of a rectangular grain-boundary potential barrier. The model also verifies the applicability of a single-crystal band diagram for the crystallite within which an impurity level exists. Carder transport includes not only thermionic field emission through the space-charge potential barrier resulting from trapping effects and through the grain-boundary scattering potential barrier but also thermionic emission over these barriers. Thermionic emission dominates at high temperatures; however, at low temperatures, thermionic field emission becomes more important and the grain-boundary scattering effects are an essential factor. By characterizing the experimental data of the I-V characteristics, resistivity, mobility, and carrier concentration, this model enhances the understanding of the current transport in polysilicon films with grain sizes from 100 Å to 1 µm, doping levels from 1 × 10 16 to 8 × 10 19 cm -3 , and measurement temperatures from -176 to 144°C. The limitations of the model are also discussed.