The effect of thermal annealing on the grain size and electrical characteristics of arsenic ion-implanted and laser-irradiated polycrystalline silicon films

Abstract

Q-switched Nd: YAG laser irradiation and subsequent thermal annealing are carried out for arsenic ion-implanted polycrystalline silicon films. Crystallographical and electrical characteristics of polycrystalline silicon are studied by using transmission electron microscopy and Hall measurements. Almost all implanted arsenic ions are electrically activated on laser irradiation, but grain growth and crystalline recovery are not found. The crystalline recovery begins to occur and carrier mobility increases during subsequent thermal annealing at temperatures of 500 °C and higher. The carrier concentration decreases due to the inactivation of the arsenic atoms with subsequent thermal annealing in the temperature range between 500 and 750 °C. At temperatures above 750 °C, grain growth and defect annihilation take place, and the carrier concentration per cm2 increases due to the diffusion and reactivation of arsenic atoms.