Measurement of boron diffusivity in hydrogenated amorphous silicon by using nuclear reaction 10B(<i>n</i>,α)7Li

Abstract

The method to measure boron profile by using the nuclear reaction 10B(n,α)7Li is applied to estimate the diffusivity of boron in the glow-discharged hydrogenated amorphous–silicon (a–Si:H). It is found that the diffusivity of boron in a–Si:H is much larger than that in crystalline silicon (c–Si). For instance, it is about 2×1016 cm2/s at 330 °C and larger than in c–Si by twelve orders of magnitude. The activation energy of the diffusivity is also estimated to be 1.5 eV. These values are nearly equal to those of hydrogen in a–Si:H. The minimum duration, in which the characteristics of p–i–n type a–Si:H solar cells may start to change due to this boron diffusion, is roughly estimated using both boron diffusivity and its activation energy.