Wide band‐gap, fairly conductivep‐type hydrogenated amorphous silicon carbide films prepared by direct photolysis; solar cell application

We have investigated a-Si,N:H alloys as an alternative wide band-gap, photo-active material. The entire alloy range between a-Si:H and a-Si3N4:H can be formed by a remote plasma-enhanced chemical-vapor deposition (PECVD) process. Other studies have demonstrated that a-Si,N:H alloys could be doped to form window materials for p-i-n devices. This paper focuses on alloy materials with E04 bandgaps to about 2.2 eV. We have prepared these a-Si,N:H alloys, characterized their microstructure, and studied their photoconductivity, sensitivity to light-soaking and transport properties. For example, with increased alloying we show that i) the white-light photoconductivity and ii) the kinetics and magnitude of the decay of photoconducitivity under intense illumination (the Staebler-Wronski effect), are about the same as for PV-grade a-Si:H.

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Growth and Characterization of Hydrogenated Amorphous Silicon using Liquid Organic Sources

MRS Proceedings ◽

10.1557/proc-219-697 ◽

1991 ◽

Vol 219 ◽

Author(s):

K. Gaughan ◽

S. Hershgold ◽

J. M. Viner ◽

P. C. Taylor

Keyword(s):

Thin Films ◽

Amorphous Silicon ◽

Hydrogenated Amorphous Silicon ◽

Wide Band ◽

Discharge Process ◽

Wide Band Gap ◽

Silicon Carbon ◽

Rf Glow Discharge ◽

Hydrogenated Amorphous

ABSTRACTThe uses of liquid sources such as tertiarybutylphosphine (TBP) for n-type doping in hydrogenated amorphous silicon (a-Si:H) and ditertiarybutylsilane (DTBS) and n-butylsilane (NBS) for hydrogenated amorphous silicon-carbon alloys (a-SiC:H) are described. A rf glow discharge process is employed to produce the doped a-Si:H and a-SiC:H thin films. Tertiarybutylphosphine (TBP) may ultimately be preferred over phosphine because TBP is less toxic, less pyrophoric and safer to implement. The gross doping properties of a-Si:H doped with TBP are the same as those obtained with phosphine, but there are some differences. N-butylsilane (NBS) and DTBS have been used to produce wide band gap (E04 3 ≈ eV) a-SiC:H.

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Hydrogenated Amorphous Silicon Alloys Prepared by CVD of Higher Silanes

MRS Proceedings ◽

10.1557/proc-70-43 ◽

1986 ◽

Vol 70 ◽

Author(s):

Masud Akhtar ◽

Herbert A. Weaklie

Keyword(s):

Amorphous Silicon ◽

Band Gap ◽

Plasma Deposition ◽

Hydrogenated Amorphous Silicon ◽

Chemical Vapor ◽

Wide Band ◽

Dark Conductivity ◽

Attractive Alternative ◽

Silicon Alloys ◽

Hydrogenated Amorphous

ABSTRACTHydrogenated amorphous silicon may be deposited at relatively low temperatures, where the density of defects may be expected to be low, by the chemical vapor deposition (CVD) of higher silanes. This method is an attractive alternative to plasma deposition techniques. We describe here the preparation of a-Si:H and related alloys incorporating carbon, germanium, and fluorine. a-Si:H films were deposited on heated substrates in the range 365°C-445°C by CVD of Si2H6 and Si3H8. The optical gap (Eg) ranged from 1.4 to 1.7 eV and the properties of films deposited from either Si2 H6 or Si3 H8 were quite similar. Wide band gap (Eg=2 eV) alloys of a-SiC:H doped with boron were prepared by CVD of disilane, methyl silane, and diborane. We also prepared variable band gap a-SiC:H alloys by substituting F2C= CFH for methylsilane, and these films were found to have approximately 1–2% fluorine incorporated. The dark conductivity of the boron doped a-SiC:H alloys dep~sited from either carbon source ranged from ix10-7 to 6x10-7 (ohm-cm)-1. We also prepared low band aap alloys of Si and Ge by CVD of trisilane and germane. The band gap of a film containing 20% Ge was 1.5 eV; however, the photoconductivity of the film was relatively low.

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