• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.1
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• pp.1-11
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• 1999

Hyrdogenated amorphous silicon thin film transistors are used as a pixel switching device of TFT-LCDs and very active research works on a-Si:H TFTs are in progress. Further development of the technology based on a-Si:H TFTs depends on the increased understanding of the device physics and the ability to accurately simulate the characteristics of them. A two-dimensional device simulator based on the realistic and flexible physical models can guide the device designs and their optimizations. A non-uniform finite-difference TFT Simulation Program, TFT2DS has been developed to solve the electronic transport equations for a-Si:H TFTs. In TFT2DS, many of the simplifying assumptions are removed. The developed simulator was used to calculate the transfer and output characteristics of a-Si:H TFTs. The measured data were compared with the simulated ones for verifying the validity of TFT2DS. Also the transient behaviors of a-Si:H TFTs were calculated even if the values of the related parameters are not accurately specified.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.8
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• pp.41-51
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• 1997

The device simulator (BANDIS) which can analyze efficiently the electrical characteristics of the semiconductor devices under the three dimensional stationary conditions on the IBM PC was developed. Poisson, electon and hole continuity equations are discretized y te galerkin method using a tetrahedron as af finite element. The frontal solver which has exquisite data structures and advanced input/output functions is dused for the matrix solver which needs the highest cost in the three dimensional device simulation. The discretization method of the continuity equations used in BANDIS are compared with that of the scharfetter-gummel method used in the commercial three-dimensional device. To verify an accuracy and the efficiency of the discretization method, the simulation results of the PN junction diode and the BJT from BANDIS are compared with those of the commercial three-dimensiional device simulator such as DAVINCI. The maximum relative error within 2% and the average number of iterations needed for the convergence is decreased by more than 20%. The total simulation time of the BJT with 25542 nodes is decreased to about 60% compared with that of DAVINCI.

• Electrical & Electronic Materials
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• v.7 no.2
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• pp.107-116
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• 1994

In the manufacturing of VLSI circuits, variations of device characteristics due to the slight differences in process parameters drastically aggravate the performances of fabricated devices. Therefore, it is very important to establish optimal process conditions in order to minimize deviations of device characteristics. In this paper, we used one-dimensional process simulator, SUPREM-II, and two dimensional device simulator, MINIMOS 4.0 in order to extract optimal process parameter which can minimize changes of the device characteristics caused by process parameter variation in the case of short channel nMOSFET and pMOSFET device. From this simulation, we have derived the dependence relations between process parameters and device characteristics. Here, we have suggested a method to extract process parameters from design trend curve(DTC) obtained by these dependence relations. And we have discussed short channel effects and device limitations by scaling down MOSFET dimensions.

• Oral Biology Research
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• v.42 no.4
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• pp.235-240
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• 2018

Standard oral and maxillofacial three-dimensional model was developed with patients' medical data while virtual reality (VR) simulator was developed in conjunction with head mount display (HMD) and Haptic device. The objective of this study was to evaluate the preclinical use of a VR training simulator in tooth preparation practice. Eighty-nine dental students were trained how to operate the simulator. The participants were then given sufficient time on the simulator to practice dental preparation. The students experience and opinion was then taken in through filling of questionnaires. On average content received 1.8 points, anatomy had 2.5 points, 2.6 points for the applicability, and 2.0 for the usability. As for the detailed items scores, queries about the possible development of the simulator and the interest of the learning process through the simulator were the highest at 3.1 and 3.0 points, respectively. Question about the benefit of the HMD and the haptic device during the practice had 1.5 and 1.6 points, respectively. The average total score was 2.2 points. VR tooth preparation simulator in the field of clinical dental education has powerful potential in regard to realistic models, environments, vision, posture, and economical efficiency.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.187-193
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• 2012

Digital X-ray image detector has been applied for medical and industrial fields. Photoconductors have been used to convert the X-ray energy to electrical signal on the direct digital X-ray image detector and amorphous selenium (a-Se) has been used as a photoconductor, normally. In this work, we use 2-dimensional device (2-D) simulator to study about physical phenomena in the a-Se, when we irradiate electromagnetic radiation (${\lambda}=486nm$) on the a-Se surface. We evaluate the electron-hole generation rate, electron-hole recombination rate, and electron/hole distribution in the a-Se using 2-D simulator. This simulator divides the device into triangle and calculates using interpolation method. This simulation method has been proposed for the first time and we expect that it will be applied for the development of digital X-ray image detector.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.2
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• pp.160-164
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• 2010

The radio frequency (RF) model of SOI FinFETs with gate length of 40 nm is verified by using a 3-dimensional (3-D) device simulator. This paper shows the equivalent circuit model which can be used in the circuit analysis simulator. The RMS modeling error of Y-parameter was calculated to be only 0.3 %.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.997-999
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• 2012

Digital X-ray image detector is widely used for radiodiagnosis. Amorphous selenium has been received attention as one of the major material that confirmed photoconductor of direct methode detector. We analysis the photocurrent using 2-dimensional device simulator when blue-ray (${\lambda}=486nm$) is irradiated and high voltage is biased. We evaluate electron-hole generation rate, electron-hole recombination rate, and electron/hole distribution in the amorphous selenium. This simulation methode is helpful to the analysis of digital X-ray image detector. We expect that many applications will be developed in digital X-ray image detector using 2-dimensional device simulator.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.7
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• pp.32-37
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• 1993

A novel insulated gate bipolar transister (IGBT), called insulated trench cathode IGBT (ISTC-IGBT), is proposed. ISTC-IGBT has a trenched well with the shallow P$^{+}$ juction in the conventional IGBT structure. The proposed structure has the capability of effectively suppressing the parasitic thyristor latchup. The holding current of ISTC-IGBT is about 2.2 times greater than that of the conventional IGBT. Detailed analysis of the latchup characteristics of ISTC-IGBT is performed by using the two-dimensional device simulator, PISCES-II B.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.1
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• pp.40-50
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• 2011

A two-dimensional (2D) analytical model for the potential distribution and threshold voltage of short-channel ion-implanted GaAs MESFETs operating in the sub-threshold regime has been presented. A double-integrable Gaussian-like function has been assumed as the doping distribution profile in the vertical direction of the channel. The Schottky gate has been assumed to be semi-transparent through which optical radiation is coupled into the device. The 2D potential distribution in the channel of the short-channel device has been obtained by solving the 2D Poisson's equation by using suitable boundary conditions. The effects of excess carrier generation due to the incident optical radiation in channel region have been included in the Poisson's equation to study the optical effects on the device. The potential function has been utilized to model the threshold voltage of the device under dark and illuminated conditions. The proposed model has been verified by comparing the theoretically predicted results with simulated data obtained by using the commercially available $ATLAS^{TM}$ 2D device simulator.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1349-1351
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• 1997

TFT2DS was utilized to provide the usefulness as an analytic and design tool. In this paper, the general effects of channel length of an inverted staggered amorphous silicon thin film transistor on its characteristics were investigated. The results obtained from these experiments would be adopted to the optimized device designs and advanced simulations of their electrical properties.