Hydrogenated microcrystalline silicon thin films can be used to fabricate stable thin
film solar cell, which were deposited by very high frequency plasma-enhanced
chemical vapor deposition at low temperatures (~200°C). It has been found that the
obtained film presented excellent structural and electrical properties, such as high
growth rate and good crystallinity. With the decreasing of silane concentration, the
optical gap and the dark conductivity increased, whereas the activation energy
decreased. A reasonable explanation was presented to elucidate these phenomena. In
addition, we fabricated p-i-n structure solar cells using the optimum microcrystalline
silicon thin films, and preliminary efficiency of 4.6% was obtained for 1
Hydrogenated microcrystalline silicon (
In our previous work, we reported that the
In this study, we focused our research on the application of 81.3 MHz VHF PECVD to improve the material properties. The effects of experimental parameters on microstructure and optoelectronic properties of the intrinsic
The
The effect of the silane concentration on the microcrystalline silicon films has been studied by varying the silane concentration (
The microstructures of the samples were characterized by Raman spectroscopy and X-ray diffraction (XRD). Raman signals were detected by a Jobin Yvon Horiba HR800 spectrometer with an excitation light source of wavelength of 532 nm. The XRD measurements were performed on a Rigaku D/Max-IIIC X-ray diffractometer in a standard
The p-i-n structure of
Schematic view of
Figure
Growth rate as a function of silane concentration for the
Figure
The results of Raman and XRD analysis for the
|
13 | 9 | 6 | 5 | 4 |
|
0 | 11.4 | 21.6 | 32.3 | 45.6 |
|
12.4 | 35.5 | 59.4 | 61.5 | 74.1 |
XRD patterns of the
Micro-Raman spectra of the
Raman spectra of the
The absorption spectra were measured by the spectrophotometer. It is well known that the optical band gap (
As is shown in Figure
Absorption coefficient
Variation of the optical band gap (
It is of significance to investigate the dependence of carriers transport behavior on the silane concentration. Figure
Dark conductivity and activation energy of the
It was reported that optimum solar cells were always found close to the transition from microcrystalline to amorphous growth, with a crystallinity of about 60% [
The current-voltage characteristic of
The
The authors declare that there is no conflict of interests regarding the publication of this paper.
This work was supported by the National Natural Science Foundation of China (Grant nos. 61106006 and 61376011), the Gansu Provincial Natural Science Foundation of China (Grant no. 1208RJZA200), and the Fundamental Research Funds for the Central Universities (Grant no. 861383).