Low temperature plasma deposition of microcrystalline silicon films for bottom gate thin film transistors

We review our studies on the growth of microcrystalline silicon films by the standard PECVD technique. In situ spectroscopic ellipsometry studies allow the optimization of the complex film structure with respect to competing aspects of the growth process. Fine tuning the hydrogen flux, the ion energy, and the nature of the species contributing to deposition produces unique films with a fully crystallized interface with silicon nitride. These materials have been successfully incorporated in bottom gate TFTs which present mobility values in the range of 1 to 3 cm²/V.s, and stable characteristics when submitted to a bias stress. The stability of these TFTs makes them suitable for driver applications in AMLCDs as well as pixel elements in OLED displays.