Crystallized amorphous silicon for low-cost solar cells

Abstract

Abstract Hydrogenated amorphous silicon (a-Si:H), 1–10 μm thick, was deposited onto stainless steel and molybdenum sheets using catholic d.c. glow discharge in a gradient field and by plasma-enhanced chemical vapor deposition. The films were subsequently crystallized by isothermal heating in N2, rapid thermal processing, isothermal annealing in vacuum (IAV) or isothermal annealing after vycor encapsulation (IAE). All techniques led to crystallization as revealed by X-ray diffraction. Annealing by IAV at 1000 °C for 7 h or IAE at 700 °C for 8 h gave the most intense (111) silicon diffraction peaks. Auger electron spectroscopy showed significant diffusion of iron into the silicon for stainless steel substrates. Energy recoil detection of as-deposited a-Si:H showed good uniformity of both silicon and hydrogen.