Infrared absorption strength and hydrogen content of hydrogenated amorphous silicon

Journal Article · Mon Jun 15 04:00:00 EDT 1992 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.45.13367· OSTI ID:7110217

Langford, A A; Fleet, M L; Nelson, B P ^[1]; Lanford, W A ^[2]; Maley, N ^[3]

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1. National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)
2. Department of Physics, State University of New York, Albany, New York 12222 (United States)
3. Coordinated Science Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)

We have used infrared transmission and nuclear-reaction analysis to determine the ir absorption strength of the Si-H wagging and stretching modes in hydrogenated amorphous silicon ({ital a}-Si:H). The films were deposited by plasma-assisted chemical vapor deposition and reactive magnetron sputtering. We show that the widely used ir-data-analysis method of Brodsky, Cardona, and Cuomo can lead to significant errors in determining the absorption coefficients, particularly for films less than {similar to}1 {mu}m thick. To eliminate these errors we explicitly take into account the effects of optical interference to analyze our data. We show that the hydrogen content can be determined from the stretching modes at {omega}=2000 and 2100 cm{sup {minus}1} as well as the wagging mode at {omega}=640 cm{sup {minus}1}. By assigning different oscillator strengths to the 2000- and 2100-cm{sup {minus}1} modes, we show that the absorption strength of the stretching modes does not depend on the details of sample preparation, contrary to hypotheses previously invoked to explain experimental data. We obtain {ital A}{sub 640}=(2.1{plus minus}0.2){times}10{sup 19} cm{sup {minus}2}, {ital A}{sub 2000}=(9.0{plus minus}1.0){times}10{sup 19} cm{sup {minus}2}, and {ital A}{sub 2100}=(2.2{plus minus}0.2){times}10{sup 20} cm{sup {minus}2} for the proportionality constants between the hydrogen concentration and the integrated absorbance of the wagging and stretching modes. The value of {ital A}{sub 640} is {similar to}30% larger than the generally used value. We show that previously published data for both the wagging and stretching modes are consistent with the proportionality factors determined in the present study.

• DOE Contract Number: AC02-83CH10093
• OSTI ID: 7110217
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 45:23; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ABSORPTION SPECTRA
AMORPHOUS STATE
CHEMICAL BONDS
CHEMICAL COATING
CHEMICAL REACTIONS
CHEMICAL VAPOR DEPOSITION
DEPOSITION
ELEMENTS
HYDROGENATION
INFRARED SPECTRA
SEMIMETALS
SILICON
SPECTRA
SPUTTERING
SUBSTOICHIOMETRY
SURFACE COATING