ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Measurements are reported on the infrared (IR) absorption, the optical band gap, and the dark conductivity of amorphous silicon-phosphorus alloy thin films (a-Si:P) with 20–44 at. % P prepared by coevaporation of Si and P. The results show that the optical band gap can be tailored in a range of 1.5–2.15 eV by varying the P concentration and the annealing temperature. The band gap for the sample with 20 at % P is the widest (1.70–1.82 eV) when annealed at temperatures ≤600 °C. From the IR-absorption study, a stretching mode associated with Si—P bonds at 465–474 cm−1 has been found for all alloy films. An evolution (shift or sharpening) of the Si—P absorption band with annealing temperature and P concentration have also been observed. Based on the IR-absorption study the change of bonding structures in the alloy films is discussed. Conductivity measurements show that two electron conduction processes mainly exist in the investigated temperature range: extended-state conduction in the conduction band at high temperatures and hopping conduction in the band tail at low temperatures. The transition temperature is around room temperature (14–55 °C), indicating that the carriers may mainly drift by hopping even at room temperature. The correlation between the optical band gap and the bonding structure is discussed. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.359392
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