Nano-second timescale high-field phase transition in hydrogenated amorphous silicon

Abstract

In this work, we report the phase transition behavior of hydrogenated amorphous silicon on the application of nanosecond timescale high-field pulse electrical stress. The transition of amorphous silicon to nanocrystalline silicon, confirmed through Raman spectroscopy, is marked by an abrupt change in the pulse I-V characteristics. The mechanism of the phase transition at high electric field involving the avalanche generation of charge carriers and optical phonon generation is discussed. The role of defect states in optical phonon localization and eventual phase transition is explored. The phase transition in the case of devices with a drain-gate underlap is also studied. The role of self-heating in accelerating the phase transition has also been explored. The impact of channel dimensions on the onset of the phase transition is also discussed. Characterization of the resultant nc-Si is done through deconvolution of the Raman spectra, and the quality of nc-Si created is found comparable to earlier studies.