Aluminum-induced crystallization of amorphous silicon (alpha-Si : H) at 150 degrees C

Thin amorphous silicon (alpha -Si:H) films (50 nm) were grown by plasma-enh anced chemical vapor deposition (PECVD) on carbon-coated nickel transmissio n electron microscope (TEM) grids. A thin layer (50 nm or less) of aluminum (Al) was then deposited on the alpha -Si:H films by vacuum evaporation. Th ese structures were then annealed at temperatures between 140 and 200 degre esC in vacuum using a lamp furnace to investigate the aluminum-induced crys tallization (AIC) of PECVD grown alpha -Si:H. The process of crystallizatio n was studied by TEM and electron diffraction (ED) and X-ray diffraction (X RD). For glancing angle XRD studies, 500 nm thick alpha -Si:H and 400 nm th ick Al films were used, and in situ annealing was performed at temperatures between 100 and 250 degreesC using a model TTK low temperature camera moun ted on the omega shaft of the goniometer of a Philips X'Pert XRD system. Th e TEM results revealed complete crystallization of the alpha -Si:H film in 30 min at an annealing temperature of 150 degreesC. The in situ XRD data al so indicate conversion of the alpha -Si:H into a crystalline silicon phase at temperatures between 150 and 160 degreesC. These results show for the fi rst time that polycrystalline silicon with grain sizes as large as 0.2 to 0 .5 mm can be obtained by AIC of PECVD alpha -Si:H at a temperature as low a s 150 degreesC. (C) 2001 The Electrochemical Society.