Aluminum-Induced Crystallization of Amorphous Silicon (α-Si:H) at 150°C

Abstract

Thin amorphous silicon (α-Si:H) films (50 nm) were grown by plasma-enhanced chemical vapor deposition (PECVD) on carbon-coated nickel transmission electron microscope (TEM) grids. A thin layer (50 nm or less) of aluminum (Al) was then deposited on the α-Si:H films by vacuum evaporation. These structures were then annealed at temperatures between 140 and 200°C in vacuum using a lamp furnace to investigate the aluminum-induced crystallization (AIC) of PECVD grown α-Si:H. The process of crystallization was studied by TEM and electron diffraction (ED) and X-ray diffraction (XRD). For glancing angle XRD studies, 500 nm thick α-Si:H and 400 nm thick Al films were used, and in situ annealing was performed at temperatures between 100 and 250°C using a model TTK low temperature camera mounted on the omega shaft of the goniometer of a Philips X'Pert XRD system. The TEM results revealed complete crystallization of the α-Si:H film in 30 min at an annealing temperature of 150°C. The in situ XRD data also indicate conversion of the α-Si:H into a crystalline silicon phase at temperatures between 150 and 160°C. These results show for the first time that polycrystalline silicon with grain sizes as large as 0.2 to 0.5 μm can be obtained by AIC of PECVD α-Si:H at a temperature as low as 150°C. © 2001 The Electrochemical Society. All rights reserved.