Characterization of thin film transistors fabricated on different sequential lateral solidified poly-silicon substrates

L.Michalas, G.P.Papaioannou, D.N.Kouvatsos, F.V.Farmakis, A.T.Voutsas
2008. Microelectronics Engineering 85, 976-978, doi: 10.1016/j.mee.2008.01.003

Abstract: Polycrystalline silicon quality is a key issue parameter for the performance and reliability of thin film transistors. Therefore in the present work, the material related electrical properties of TFTs fabricated on films crystallized by two different SLS–ELA procedures, 1-shot/overlapped irradiated, yielding different film textures, are investigated. The study employed devices with channel alighted across different orientation on the film. The transfer characteristics have been recorded and analyzed in the linear operation regime and temperature range of 120–440 K. The temperature dependence of typical parameters such as the sub-threshold swing and the leakage current is determined by the thermal generation of carriers through bang gap states, thus this study could provide information on the nature of these states. Furthermore the temperature dependence of mobility is related to scattering processes. The results suggest that TFTs fabricated on overlapped irradiated crystallized films exhibit similar performance independent of the channel orientation, while the highest mobility overall is obtained in devices fabricated across the preferable direction of 1-shot irradiated crystallized films.

Keywords: Polycrystalline silicon, SLS–ELA, TFT