Characterization of Microcrystalline Transition from Amorphous Silicon as a Function of Hydrogen Dilution and Substrate Temperature of Hot-Wire CVD

Keda Wang, Haoyue Zhang, Jian Zhang, Jessica M. Owens, Jennifer Weinberg-Wolf, Daxing Han, Lynn Gedvilas, Brent Nelson

Research output: Contribution to conferencePaperpeer-review

Abstract

a-Si:H films were prepared by hot wire chemical vapor deposition. One group was deposited at a substrate temperature of Ts=250°C with varied hydrogen-dilution ratio, O<R<10; the other group was deposited with fixed R=3 but a varied Ts from 150 to 550°C. IR, Raman and PL spectra were studied. The Raman results indicate that there is a threshold value for the microstructure transition from a- to μc-Si. The threshold is found to be R ≈ 2 at Ts = 250°C and Ts ≈ 200°C at R=3. The IR absorption of Si-H at 640 cm-1 was used to calculate the hydrogen content, CH. CH decreased monotonically when either R or Ts increased. The Si-H stretching mode contains two peaks at 2000 and 2090 cm-1. The ratio of the integral absorption peaks I2090/(I2090+I2090) showed a sudden increase at the threshold of microcrystallinity. At the same threshold, the PL features also indicate a sudden change from a- to μc-Si., i.e. the low energy PL band becomes dominant and the PL total intensity decreases. We attribute the above IR and PL changes to the contribution of microcrystallinity, especially the c-Si gain-boundaries.

Original languageAmerican English
Pages147-152
Number of pages6
DOIs
StatePublished - 2002
EventAmorphous and Heterogeneous Silicon Films 2002 - San Francisco, CA, United States
Duration: 2 Apr 20025 Apr 2002

Conference

ConferenceAmorphous and Heterogeneous Silicon Films 2002
Country/TerritoryUnited States
CitySan Francisco, CA
Period2/04/025/04/02

NREL Publication Number

  • NREL/CP-520-34494

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