Effect of long-term He–Ne laser light exposure and subsequent annealing on hydrogenated amorphous silicon pin photodiodes
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Changes in the current-voltage (IV) characteristics were monitored on as prepared a-Si:H pin photodiodes during 60 min He-Ne laser illumination (every 15 min in situ measurements). After illumination was over, the pin diodes were subjected to 1 h annealing at 200 °C and IVs were taken again. Results showed that the short circuit current (Isc) decreased with the He-Ne exposure time which is known as a Stabler-Wronski effect of degradation and increased after the annealing. In order to describe the origin of this phenomenon, a 1 νm thick a-Si:H film was deposited on Mo-coated glass sheets by plasma enhanced chemical vapour deposition (PECVD) using the same procedure as that of the i-type layer in the pin diodes. Fourier transform infrared spectra (FTIR) were taken on the sample before and after the 1 h He-Ne laser exposure as well as after annealing for 1 h at 200 °C in air. Hydrogen (H) concentration in the film was estimated from the typical Si-H vibration absorbance peak at 2000 cm-1. The results showed that the H-concentration decreases from the initial value of about 10%, to about 7% after the 1 h He-Ne laser exposure. After the thermal annealing, the hydrogen concentration increased to about 9%. The above hydrogen concentration change was directly related to the change in the IV characteristics of the pin a-Si:H diode. © 2005 IOP Publishing Ltd.
author list (cited authors)
Ristova, M., Kuo, Y., Lee, H. H., & Tewg, J. Y.