Deposition of device quality amorphous silicon by hot-wire CVD
In this paper the authors present the results of the optimization of hydrogenated amorphous silicon films deposited by the hot-wire method in a larger area system. Using a two-wire design, they succeeded in depositing films that exhibit uniform electrical properties over the whole 4 x 4 inch Corning 7059 glass substrate. At a substrate temperature of 430 C and a pressure of 20 {micro}bar they obtained a growth rate of {approximately}2 nm/s. The temperature of the tungsten filaments was kept at 1,850 C. The values for the photoconductivity and dark conductivity were 8.9 x 10{sup {minus}6} S/cm and 1.6 x 10{sup {minus}10} S/cm respectively, whereas the ambipolar diffusion length, as measured with the Steady-State Photocarrier Grating technique (SSPG), amounted to 145 nm. This value is higher than for their device quality glow-discharge (GD) films, which yield devices with efficiencies higher than 10%. The hydrogen content was 9.5%. They report on the density-of-states (DOS) distribution in the films, which was measured with the techniques of Thermally Stimulated Conductivity (TSC) and Constant Photocurrent Method (CPM). Furthermore, they describe the behavior of the electrical properties on light-induced degradation. Finally, they incorporated these films in solar cells, using conventional GD doped layers. Preliminary SS/n-i-p/ITO devices yielded efficiencies in excess of 3% under 100 mW/cm{sup 2} AM1.5 illumination. Further work concerning the optimization of the interfaces is in progress.
- Research Organization:
- Utrecht Univ. (NL)
- Sponsoring Organization:
- Netherlands Organization for Energy and Environment
- OSTI ID:
- 20085544
- Country of Publication:
- United States
- Language:
- English
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