Browsing by Author "Kuo, YK"

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A numerical study of dc characteristics of HEMT with p-type delta-doped barrier
(2005-09-01)
Chang, Y
;
Kuo, YK
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The dc characteristics of an InGaP/InGaAs/GaAs pseudomorphic high-electron-mobility transistor (HEMT) with a p-type delta-doped InGaP barrier are numerically investigated with the ISE-TCAD simulation program. The simulation results indicate that a HEMT with such a structure has a higher gate turn-on voltage, better carrier confinement that results in a lower voltage-dependent transconductance, and a larger breakdown voltage when compared with the typical HEMT. The simulation results also suggest that this structure is beneficial for linear and large-signal application.
Analysis of instability in a critical dimension bar due to focus and exposure
(2005-08-01)
Kuo, YK
;
Chao, CG
;
Lin, CY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
in the photolithography processing of semiconductor, the line width becomes smaller and smaller. Therefore, the requirements of process window are stricter than before. Among them, the control of focus and exposure dose is one of the most important factors that may affect the line width. Bad control of focus and exposure may not only affect line width. but also cause the increment of rejects of products. The research mainly explored the effects of focus and exposure dose on line widths of different photo resists. The research obtained related coefficients of exposure dose line width and focus line width by coating photo resist of different components on the surface of the silica wafer. The results of research found that focus may not only change line width but also had a positive-negative symmetric relationship with line width. It also found that there was linear relationship between exposure dose and line width. (c) 2004 Elsevier Ltd. All rights reserved.
Analysis of instability line width and white wall created by the photolithography process
(2004-11-01)
Kuo, YK
;
Chao, CG
;
Lin, CY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In the photolithography processing of semiconductor, line width is smaller and smaller. Therefore, the requirements of process window are stricter than before. In the small line width, the formation of serious white wall will affect line width and cause rejects in following process. The study conducted research on the control of best focus in which particularly explored the relationship between exposure dose and line width and the phenomenon of white wall generated by focus. The research obtained related coefficients of exposure dose-line width and exposure dose-white wall by coating photo resist of different components with the same thickness on the surface of fused silica wafer. The results of research found that exposure dose might not only change line width but also had important effects on white wall. Among others, the most important factor for exposure dose is the component of sensitivity of photo resist. (C) 2004 Elsevier Ltd. All rights reserved.
Analysis of the effects of reflectance and refraction generated by wafers made from fused silica, ALOxNy and TiSixNy under different light sources on pattern length and best focus
(2005-01-01)
Kuo, YK
;
Chao, CG
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In semi-conductor photo-lithography processing, line-width is constantly shrinking. That is why process window requirements are becoming stricter. Under these strict conditions, the influences of focus and pattern length are more important. This investigation tries to explore the deviation of best focus and the variation in pattern length resulting from the reflectance and refraction of fused silica, ALOxNy and TiSixNy wafers are coated with the same thickness of SEPR 432 PR (Photo Resist). Experimental results indicate that after excluding the influence of photo resist impacts, the refraction generated by the auto focus light source(halogens lamp) causes deviation of the best focus, and the extent of deviation has a directly proportion relationship with refraction, and no direct relationship exists between exposure light source (laser) and the deviation of best focus. The reflectance generated by exposure light source only changes the measures of pattern length, and an inverse relationship exists between reflectance and pattern length; that is, received pattern length reduces with increasing wafer reflectance. (C) 2004 Elsevier Ltd. All rights reserved.
Improvement in instable analysis of heat inflation induced line-width after replacing pellicle with diamond film on reticle (photo-masks)
(2005-04-01)
Kuo, YK
;
Chao, CG
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材料科學與工程學系
;
Department of Materials Science and Engineering
A new reticle is designed that takes advantage of the high value of thermal conductivity of diamond to add a layer of diamond film to the bottom of traditional pellicle-reticle; that is, the new reticle replaces the pellicle with a diamond material. This method may help maintain the future manufacturing process of photo-lithography below 35 nm and can improve the problem of slightly out of shape reticle caused by the long-term effects of light and thermal energy. (c) 2004 Elsevier B.V. All rights reserved.
Improving high-temperature performance in continuous-wave mode InGaAsN/GaAsN ridge waveguide lasers
(2005-06-01)
Chang, YA
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Kuo, HC
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Lu, CY
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Kuo, YK
;
Wang, SC
Continuous-wave (CW) mode operation InGaAsN/GaAsN double-quantum-well lasers with a laser wavelength of 1.295 mu m are demonstrated by metal-organic chemical vapour deposition (MOCVD). With the use of a high-bandgap GaAs0.9P0.1 into the active region before the growth of p-type layers, a room temperature (RT) threshold current of 99 mA and the characteristic temperature (TO) values of 155 K in a temperature range of 25-95 degrees C and 179 K in a temperature range of 25-85 degrees C are obtained from a 4 x 1000 mu m(2) ridge waveguide uncoated laser diode. The To value of the conventional structure without the high-bandgap GaAs0.9P0.1 is 118 K in a temperature range of 25-95 degrees C. High-temperature performance is improved and the results of numerical analysis suggest that it may be attributed to the reduced electronic leakage current.
Simulation of InGaN quantum well laser performance using quaternary InAlGaN alloy as electronic blocking layer
(2005-11-01)
Chang, YA
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Luo, CY
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Ku, HC
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Kuo, YK
;
Lin, CF
Laser performance of an InGaN edge-emitting laser using a quaternary InAlGaN electronic blocking layer is investigated. Varying the aluminum (Al) composition in InAlGaN with a fixed indium (In) value (Al : In = 5 : 1) indicates that a lower threshold current and higher characteristic temperature (T(0)) value can be obtained when the Al composition is higher than 20%. When Al = 25%, the threshold current is reduced at the expense of a decreased To value from 149 to 130 K when the In composition increases from 1 to 7% in a temperature range of 300-370 K. The decreased T(0) value is mainly attributed to the increase in electronic leakage current.
Theoretical and experimental analysis on InAlGaAs/AlGaAs active region of 850-nm vertical-cavity surface-emitting lasers
(2006-01-01)
Chang, YA
;
Chen, JR
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Kuo, HC
;
Kuo, YK
;
Wang, SC
In this study, the gain-carrier characteristics of In0.02Ga0.98As and InAlGaAs quantum wells (QWs) of variant In and Al compositions with an emission wavelength of 838 nm are theoretically investigated. More compressive strain, caused by higher In and Al compositions in InAlGaAs QW, is found to provide higher material gain, lower transparency carrier concentration, and transparency radiative current density over the temperature range of 25-95 degrees C. To improve the output characteristics and high-temperature performance of 850-nm verticalcavity surface-emitting laser (VCSEL), In(0.15)AI(0.08)Ga(0.77)As/ Al0.3Ga0.7As is utilized as the active region, and a high-bandgap 10-nm-thick Al-0.75 Ga0.25As electronic blocking layer is employed for the first time. The threshold current and slope efficiency of the VCSEL with A(10.7)SGa(0.25)As at 25 degrees C are 1.33 mA and 0.53 W/A, respectively. When this VCSEL is operated at an elevated temperature of 95 C, the increase in threshold current is less than 21 % and the decrease in slope efficiency is approximately 24.5%. A modulation bandwidth of 9.2 GHz biased at 4 mA is demonstrated.