• Journal of the Korean Solar Energy Society
• /
• v.39 no.1
• /
• pp.11-19
• /
• 2019

Spectroscopic ellipsometry is a powerful tool for analyzing optical properties of material. Ellipsometry measurement results is usually given by change of polarization state of probe light, so the measured result should be properly treated and transformed to meaningful parameters by transformation and modeling of the measurement result. In case of hydrogenated amorphous silicon, Tauc-Lorentz dispersion is usually used to model the measured ellipsometry spectrum. In this paper, modeling of spectroscopic ellipsometry result of hydrogenated amorphous silicon using Tauc-Lorentz dispersion is discussed.

• Journal of Ceramic Processing Research
• /
• v.13 no.spc2
• /
• pp.336-340
• /
• 2012

Wide band gap p-type hydrogenated amorphous silicon oxide (a-SiO:H) buffer layer has been used at the interface of transparent conductive oxide (TCO) and hydrogenated amorphous silicon (a-Si:H) p-type layer of a p-i-n type a-Si:H solar cell. Introduction of 5 nm thick buffer layer improves in blue response of the cell along with 0.5% enhancement of photovoltaic conversion efficiency (η). The cells with buffer layer show higher open circuit voltage (Voc), fill factor (FF), short circuit current density (Jsc) and improved blue response with respect to the cell without buffer layer.

• Journal of the Korean Solar Energy Society
• /
• v.39 no.1
• /
• pp.1-9
• /
• 2019

Light induced degradation is one of the major research challenges of hydrogenated amorphous silicon related thin film silicon solar cells. Amorphous silicon shows creation of metastable defect states, originating from elevated concentration of dangling bonds during light exposure. The metastable defect states work as recombination centers, and mostly affects quality of intrinsic layer in solar cells. In this paper we present results of light induced degradation in thin film silicon solar cells and discussion on physical origin, mechanism and practical solutions of light induced degradation in thin film silicon solar cells. In-situ light-soaking IV measurement techniques are presented. We also present thin film silicon material with silicon nano-quantum dots embedded within amorphous matrix, which shows superior stability during light-soaking. Our results suggest that solar cell using silicon nano-quantum dots in abosrber layer shows superior stability under light soaking, compared to the conventional amorphous silicon solar cell.

• Electrical & Electronic Materials
• /
• v.7 no.2
• /
• pp.94-99
• /
• 1994

The purpose of this work is to investigate the interface characteristics of hydrogenated amorphous silicon thin films prepared by PECVD and photo-induced CVD and to examine the annealing effects of ultraviolet irradiation on hydrogenated amorphous silicon thin films which were degraded by visible light illumination. The interface layer thickness of films deposited by photo-induced CVD was about 600-900.angs. while that by PECVD was about 1000-1300.angs.. These results can show that the quality of interface layer in photo induced CVD film is better than that in PECVD sample. The electrical properties are improved by ultraviolet irradiation on visible light soaked a-Si:H films using photo-CVD light sources, probably due to the fact that UV generates phonons in a-Si:H films and anneal the meta stable defects.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.4C no.4
• /
• pp.185-189
• /
• 2004

The temporal variation of a secondary electron emission coefficient (${\gamma}$ coefficient) of hydrogenated amorphous silicon (a-Si:H) was investigated in a dc silane plasma. Estimated ${\gamma}$ coefficients have a value of 2.73 ${\times}$ 10$^{-2}$ on the pure aluminum electrode and 1.5 ${\times}$ 10$^{-3}$ after 2 hours deposition of -Si:H thin films on a cathode. It showed an abrupt decrease for about 30 minutes before saturation. The variation of the ${\gamma}$ coefficient was estimated as a function of the thin film thickness, and the film thickness was about 80 nm after 30 minutes deposition time. These results are compared with the results of a computer simulation for ion penetration into a cathode.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.1
• /
• pp.16-19
• /
• 2013

Frequency filters with various filtering wavelengths were used in the photoelectric characterization of hydrogenated amorphous silicon thin film transistor (a-Si:H TFT) and the experimental results were described and analyzed in terms of the photon energy spectral characteristics calculated from the integration of the photon energy and the spectral intensity of transmitted backlight through the filters at each wavelength. From the comparison of the photocurrents and the calculated photon energy spectrums for the filtered ranges of wavelength, it was possible to conclude that the photocurrents are closely related to the photon energy spectrums of the backlight.

• Journal of information and communication convergence engineering
• /
• v.1 no.1
• /
• pp.23-26
• /
• 2003

A photodiode capable of obtaining a sufficient photo/dark current ratio at both a forward bias state and a reverse bias state is proposed. The photodiode includes a glass substrate, an aluminum film formed as a lower electrode over the glass substrate, an alumina film formed as a schottky barrier over the aluminum film, a hydrogenated amorphous silicon film formed as a photo conduction layer over a portion of the alumina film, and a transparent conduction film formed as an upper electrode over the hydro-generated amorphous silicon film. Growth of high quality alumina($Al_{2}O_{3}$) film using anodizing technology is proposed and analyzed by experiment. We have obtained the film with a superior characteristics

• Proceedings of the KIEE Conference
• /
• 1987.07a
• /
• pp.497-500
• /
• 1987

Photoconductive properties of B-doped hydrogenated amorphous silicon thin films prepared by the RF glow discharge decomposition of $SiH_4-B_2H_6$ gas mixtures have been investigated. Experimental results showed that the B-doped hydrogenated amorphous silicon thin films have high photosensitivity and good optical absorption. Therefore these thin films can be used for the photoconductive layer of the vidicon target.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1995.05a
• /
• pp.973-979
• /
• 1995

The input equivalent noise charge (ENC) of hydrogenated amorphous silicon radiation detector diodes was measured and analyzed. The noise sources of amorphous silicon diodes were analyzed into three sources; shot noise, flicker noise and thermal noise from the contact resistance. By comparing the measured ENC with the calculated signal charge in uniform generation case, the signal-to-noise ratio (S/N) for the sample diodes is estimated as a function of the detector bias and the shaping time of Gaussian pulse shaper. The maximum S/N occurred at the bias level just above the full depletion voltage for shaping time of 2∼3 ${\mu}$sec. The developed method is useful in optimum design or amorphous silicon p-i-n diodes for charged particulate radiation spectroscopy.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.24 no.3
• /
• pp.453-458
• /
• 1987

Amorphous silicon thin-film transtors (TFT's) have been designed and fabricated on glass substrates. The hydrogenated amorphous silicon (a-Si:H) thin-film has been deposited by decomposing silane(SiH4) in hydorgen ambient by rf glow discharge method. Amorphous silicon nitride(a-Si:H) has been chosen as the gate dielectric material. It has been prepared by decomposing the mixed gas of silane(SiH4) and ammonia(NH3). The electrical properties and performance characteristics of the thin-film transistrs have been measured and compared with the requirements for the switching elements in liquid crystal flat panel display. The results show that liquid crystal flat panel displays can be fabricated using the thin-film transistors described in this paper.