• Journal of Sensor Science and Technology
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• v.9 no.1
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• pp.1-8
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• 2000

One of today's very critical and sensitive accurate accelerometer which can be used higher temperature than $200^{\circ}C$ and corrosive environment, is particularly demanded for automotive engine. Because silicon is a material of large temperature dependent coefficient, and the piezoresistors are isolated with p-n junctions, and its leakage current increase with temperature, the performance of the silicon accelerometer degrades especially after $150^{\circ}C$. In this paper, The temperature characteristic of a accelerometer using silicon on insulator (SOI) structure is studied theoretically, and compared with experimental results. The temperature coefficients of sensitivity and offset voltage (TCS and TCO) are related to some factors such as thermal residual stress, and are expressed numerically. Thermal stress analysis of the accelerometer has also been carried out with the finite-element method(FEM) simulation program ANSYS. TCS of this accelerometer can be reduced to control the impurity concentration of piezoresistors, and TCO is related to factors such as process variation and thermal residual stress on the piezoresistors. In real packaging, The avarage thermal residual stress in the center support structure was estimated at around $3.7{\times}10^4Nm^{-2}^{\circ}C^{-1}$ at sensing resistor. The simulated ${\gamma}_{pT}$ of the center support structure was smaller than one-tenth as compared with that of the surrounding support structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.440-443
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• 2002

Present1y the X-Ray diagnosis system is a real condition that is changing by digital ways in it's existent analog ways. This digital radiation detector is divided by the direct method and the indirect method. The indirect method of applied voltage has special qualities that the resolution is low than direct method by diffusion effect that happens. The conversion process ( radiation${\rightarrow}$visible ray${\rightarrow}$electrical signal of two times, has shortcomings that the energy conversion efficiency of electrical signal is low. The direct method has shortcomings that need strong electric fie1d to detect electrical signal efficiently. This research achieved to develop digital detector of the Hybrid method that have form that mixes two ways to supplement shortcoming of direct. indirect method. A studied electrical characteristic by Iodine's Mixture ratio change is added to selenium in the detector which has a multi-layer structure (Oxybromide + a-Se). There are 8 kinds of Manufactured compositions to amorphous selenium Iodine each 30ppm, 100ppm, 200 ppm, 300ppm, 400ppm, 500ppm, 600ppm, 700ppm by a doped photoconductor through a vacuum thermal evaporation method. The phosphor layer is consisted of Oxybromide ($BrO_2$) which uses optical adhesives multi-layer structure. The manufactured compositions calculates and compares Net Charge and signal to noise ratio measuring Photocurrent about Darkcurrent and X-ray. When doped Iodine Mixture ratio is 500ppm to the multi-layer structure (Oxybromide + a-Se), applied voltage of $3V/{\mu}m$, leakage current of compositions $2.61nA/cm^2$ and net charge value by 764pC/$cm^2$/mR then the best result appeared.