Effect of boron on the microstructure of hydrogenated microcrystalline silicon thin films

Abstract

In this work, a series of boron doped microcrystalline silicon films (µc-Si:H (B)) were deposited by plasma-enhanced chemical vapor deposition (PECVD), using silane (SiH4) diluted in hydrogen, and diborane (B2H6) as a dopant gas. The concentration of B2H6 was varied in the range of 0–100 ppm. The microstructure and morphology of samples were analyzed by atomic force microscopy (AFM), X-ray diffraction (XRD), and Raman spectroscopy. A trend towards increasing crystalline volume fraction and grain size were observed as boron concentration in the samples increased; while the XRD spectra show that the peak intensity at 2? ˜ 47° decreases and becomes gradually amorphous with the increasing degree of doping. The doped microcrystalline silicon films presented a crystallographic preferential orientation in the plane (220). Correlations between structural and electric properties were also studied.