N-type polycrystalline silicon films obtained by crystallization of in situ phosphorus-doped amorphous silicon films deposited at low pressure

Abstract

The low-pressure chemical-vapor deposition of phosphorus-doped silicon film on glass at 550 °C was investigated as a function of silane pressure (1–100 Pa) and phosphine/silane mole ratio ranging between 4×10−6 and 4×10−4. At this low temperature the film is homogeneous in thickness and the silicon is amorphous except for low pressure (1 Pa). Phosphorus concentration varies linearly with mole ratio in amorphous deposited films. The resistivity of films annealed at 600 °C decreases while the incorporation of phosphorus (mole ratio) increases, and varies with phosphorus concentration from 101 to 10−3 Ω cm. For the same phosphorus content, the resistivity is lower if the silicon film is amorphous deposited and subsequently crystallized, than if the film is polycrystalline deposited. Carrier concentration and mobility are measured using the Hall method. Doping efficiency and electrical properties are discussed.