A semi-empirical model for the field-effect mobility of hydrogenated polycrystalline-silicon MOSFETs

Abstract

The quantitative relationship between field-effect mobility ( mu /sub FE/) and grain-boundary trap-state density (N/sub t/) in hydrogenated polycrystalline-silicon (poly-Si) MOSFETs is investigated. The focus is on the field-effect mobility in MOSFETs with N/sub t/ 1*10/sup 2/ cm/sup -2/. It is found that reducing N/sub t/ to as low as 5*10/sup 11/ cm/sup -2/ has a great impact on mu /sub FE/. MOSFETs with the N/sub t/ of 4.2*10/sup 11/ cm/sup -2/ show an electron mobility of 185 cm/sup 2//V-s, despite a mean grain size of 0.5 mu m. The three principal factors that determine mu /sub FE/, namely, the low-field mobility, the mobility degradation factor, and the trap-state density N/sub t/ are clarified.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>