Polycrystalline silicon thin films on glass by aluminum-induced crystallization

This work focuses on the development and characterization of device quality thin-film crystalline silicon layers directly onto low-temperature glass. The material requirements and crystallographic quality necessary for high-p erformance device fabrication are studied and discussed. The processing tec hnique investigated is aluminum-induced crystallization (AIC) of sputtered amorphous silicon on Al-coated glass substrates. Electron and ion beam micr oscopy are employed to study the crystallization process and the structure of the continuous polycrystalline silicon laver, The formation of this laye r is accompanied by the juxtaposed layers of Al and Si films exchanging pla ces during annealing, The grain sizes of the poly-Si material are many time s larger than the film's thickness. Raman and thin-film X-ray diffraction m easurements verify the good crystalline quality of the Si layers, The elect rical properties are investigated by temperature dependent Hall effect meas urements. They show that the electrical transport is governed by the proper ties within the crystallites rather than the grain boundaries. The specific advantages of AIC are: 1) its simplicity and industrial relevance, particu larly for the processes of sputter deposition and thermal evaporation, 2) i t requires only low-temperature processing at 500 degrees C, 3) its short p rocessing times, and li its ability to produce polycrystalline material wit h good crystallographic and electrical properties. These advantages make th e poly-Si material formed by AIC highly interesting and suitable for subseq uent device fabrication such as for poly-Si thin-film solar cells.