Boron-doped nanocrystalline silicon thin films for solar cells

Abstract

This article reports on the structural, electronic, and optical properties of boron-doped hydrogenated nanocrystalline silicon (nc-Si: H) thin films. The films were deposited by plasma-enhanced chemical vapour deposition (PECVD) at a substrate temperature of 150 degrees C. Crystalline volume fraction and dark conductivity of the films were determined as a function of trimethylboron-to-silane flow ratio. Optical constants of doped and undoped nc-Si: H were obtained from transmission and reflection spectra. By employing p(+) nc-Si: H as a window layer combined with a p' a-SiC buffer layer, aSi: H-based p-p'-i-n solar cells on ZnO:Al-coated glass substrates were fabricated. Device characteristics were obtained from current-voltage and spectral-response measurements.

Investigation of p-type nanocrystalline silicon emitters for silicon heterojunction solar cells

“…It can be seen that d and X c increase sharply in the narrow thickness range from 10 nm to 20 nm, and then rises slowly when further increasing film thickness to 130 nm. Similar thickness dependence of the conductivity was also reported by other groups [3,36]. This can be interpreted in terms of percolation theory by formation of a percolation cluster composed of Si nanocrystallites as the film thickness becomes comparable to the grain size [37].…”

“…Hydrogenated nanocrystalline silicon (nc-Si:H) has several advantages over hydrogenated amorphous silicon with respect to shallower Fermi level, higher conductivity and lower optical absorption loss in the visible range [3,4]. And the use of nc-Si:H thin films as the emitter layer in SHJ solar cells ensures a high open circuit voltage (V oc ), a good fill factor (FF), and an ideal short circuit current (I sc ) in theory.…”

Wide bandgap p-type window layer prepared by trimethylboron doping at high temperature for a-Si:H superstrate solar cell

“…Currently, trimethylboron (TMB) is being paid much attention as a better alternative to diborane for the p-layer doping [13][14][15]. TMB has a superior thermal stability than diborane, and does not decompose into elementary boron in hot zones without plasma contact.…”

Annealing effects on electrical and optical properties of a-Si:H layer deposited by PECVD

“…In recent years, hydrogenated nanocrystalline Si (nc-Si), obtained either by growth process [19] or by thermal annealing [20], is considered as one of the most promising materials for photovoltaic application mainly due to its potential application in future optoelectronic devices [21]. So far, the electronic and optical properties of nc-Si have been extensively investigated.…”