• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.5
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• pp.501-508
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• 1988

This paper presents the light-induced effects on the elelctrical and optical properties of undoped and doped hydrogenated amorphous silicon films. The changes in the conductivities and the activation energies of various types of a-Si:H films due to the prolonged exposure to light have been characterized as a function of deposition conditions and illumination periods. The dark conductivity changes may be quenched for heavier doped a-Si:H films. We have also analyzed the variations of micro-structure of a-Si:H film such as silicon-hydrogen bondings in the rocking and stretching modes utilizing infrared spectroscopy. From the experimental results, it is elucidated that doping effects must be crucial to the degradations of the fundamental properties of a-Si:H due to light-induced effects.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.2
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• pp.146-149
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• 2017

Si clusters generated during the plasma chemical vapor deposition (CVD) process have a great influence on the quality of the fabricated films. In particular, in hydrogenated amorphous silicon thin films (a-Si:H) used for thin film solar cells, Si clusters are mainly responsible for light-induced degradation. In this study, we investigated the amount of clusters incorporated into thin films using a quartz crystal microbalance (QCM) and specially designed cluster eliminating filters, and investigated the effect of the DC grid mesh in preventing cluster incorporation. Experimental results showed that as the applied voltage of the grid mesh, which is placed between the electrode and the QCM, decreased, the number of clusters incorporated into the film decreased. This is due to the electrostatic force from the grid mesh bias, and this method is expected to contribute to the fabrication of high-quality thin films by preventing Si cluster incorporation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.5
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• pp.531-539
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• 1991

We develop an analytical model of the static and the dynamic characteristics of amorphous silicon thin film transistors (a-Si TFTs) in order to incorporate into a widely used circuit simulator such as SPICE. The critical parameters considered in our analytical model of a-Si TFT are the power factor (XN) of saturation source-drain current and the effective channel length (L') at saturation region. The power factor, XN must not always obey so-called

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.729-732
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• 2006

The effect of stress match between silicon nitride ($SiN_2$) and hydrogenated amorphous silicon (a-Si:H) layers on the electrical characteristics of thin-film transistors (TFTs) has been investigated. The result shows that modifying the deposition conditions of a Si:H and $SiN_2$ thin films can reduce the stress mismatch at a-Si:H/SiNx interface. Moreover, for best a-Si:H TFT characteristics, the internal stress of gate $SiN_2$ layer with slightly nitrogen-rich should be matched with that of a-Si:H channel layer. The ON current, field-effect mobility, and stability of TFTs can be enhanced by controlling the stress match between a-Si:H and gate insulator. The improvement of these characteristics appears to be due to both the decrease of the interface state density between the a-Si:H and SiNx layer, and the good dielectric quality of the bottom nitride layer.

• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.295-300
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• 2016

To investigate the thermal conductivity and the structural properties of naturally cooled excimer-laser annealed Si, molecular-dynamics (MD) simulations have been performed. The thermal conductivity of crystalline Si (c-Si) was measured by direct method at 1000 K. Steady-state heat flow was measured using a stationary temperature profile; significant deviations from Fourier's law were not observed. Reliable processes for measuring the thermal conductivity of c-Si were presented. A natural cooling process to admit heat flow from molten Si (l-Si) to c-Si was performed using an MD cell with a size of $48.9{\times}48.9{\times}97.8{\AA}^3$. During the cooling process, the temperature of the bottom $10{\AA}$ of the MD cell was controlled at 300 K. The results suggest that the natural cooling system described the static structural property of amorphous Si (a-Si) well.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.172-175
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• 2009

n-type crystalline silicon wafers were passivated with intrinsic a-Si:H thin films on both sides using HWCVD. Minority carrier lifetime measurement was used to verify interface passivation properties between a-Si:H thin film and crystalline Si wafer. Thin film interface characteristics were investigated depending on $H_2/SiH_4$ ratio and hot wire deposition temperature. Vacuum annealing were processed after deposition a-Si:H thin films on both sides to investigate thermal effects from post process steps. We noticed the effect of interface passivation properties according to $H_2/SiH_4$ ratio and hot wire deposition temperature, and we had maximum point of minority carrier lifetime at H2/SiH4 10 ratio and $1600^{\circ}C$ wire temperature.

• Nuclear Engineering and Technology
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• v.28 no.4
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• pp.397-404
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• 1996

The hydrogenated amorphous silicon (a-Si : H) holds good promise for radiation detection from its inherent merits over crystalline counterpart. For the application to alpha spectroscopy, the induced charge collection in a-Si : H pin detector diodes ons simulated based on a relevant non-uniform charge generation model. The simulation was peformed for the initial energy and the range of incident alpha particles, detector thickness and the operational parameters such as the applied reverse bias voltage and shaping time. From the simulation, the total charge collection was strongly affected by hole collection as expected. To get a reasonable signal generation, therefore, the hole collection should be seriously considered for detector operational parameters such as shaping time and reverse voltage etc. For the spectroscopy of alpha particle from common alpha sources, the amorphous silicon should have about 70${\mu}{\textrm}{m}$ thickness.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.112-116
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• 2007

We have investigated the hysteresis phenomenon of a hydrogenated amorphous silicon thin film transistor (a-Si:H TFT) and analyzed the effect of hysteresis phenomenon when a-Si:H TFT is a pixel element of active matrix organic light emitting diode (AMOLED). When a-Si:H TFT is addressed to different starting gate voltages, such as 10V and 5V, the measured transfer characteristics with 1uA at $V_{DS}$ = 10V shows that the gate voltage shift of 0.15V is occurred due to the different quantities of trapped charge. When the step gate-voltage in the transfer curve is decreased from 0.5V to 0.05V, the gate-voltage shift is decreased from 0.78V to 0.39V due to the change of charge do-trapping rate. The measured OLED current in the widely used 2-TFT pixel show that a gate-voltage of TFT in the previous frame can influence OLED current in the present frame by 35% due to the change of interface trap density induced by different starting gate voltages.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.196-200
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• 2005

In this work, we investigated simple Aㅣ/TCO/a-Si:H(n)/c-Si(p)/Al hetero-junction solar cells prepared by low temperature processes, unlike conventional thermal diffused c-Si solar cells. a-Si:H/c-Si hetero-junction solar cells are processed by low temperature deposition of n-type hydrogenated amorphous silicon (a-Si:H) films by plasma-enhanced chemical vapor deposition on textured and flat p-type silicon substrate. A detailed investigation was carried out to acquire optimization and compatibility of amorphous layer, TCO (ZnO:Al) layer depositions by changing the plasma process parameters. As front TCO and back contact, ZnO:Al and AI were deposited by rf magnetron sputtering and e-beam evaporation, respectively. The photovoltaic conversion efficiency under AMI.5 and the quantum efficiency on $1cm^2$ sample have been reported. An efficiency of $12.5\%$ is achieved on hetero-structure solar cells based on p-type crystalline silicon.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.2
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• pp.65-72
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• 2012

Aluminum induced crystallization of amorphous silicon was attempted by the aluminum substrate. To avoid the layer exchange between silicon and aluminum layer, Ni layer was deposited between these two layers by sputtering. To obtain the bigger grain of the crystalline silicon, wet blasted silica layer was employed as windows between the nickel and a-Si layer. Ni obtained after the annealing treatment at $520^{\circ}C$ was found to be a promising material for the diffusion barrier between silicon and aluminum. One way to obtain bigger grain of crystalline silicon layer applicable to solar cell of higher performance was envisioned in this investigation.