Browsing by Author "Chang, SJ"

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1.3-mu m InAs-InGaAs quantum-dot vertical-cavity surface-emitting laser with fully doped DBRs grown by MBE
(2006-01-01)
Yu, HC
;
Wang, JS
;
Su, YK
;
Chang, SJ
;
Lai, FI
We report InAs-InGaAs quantum-dot vertical-cavity surface-emitting lasers (VCSELs) grown by molecular beam epitaxy with fully doped n- and p-doped AlGaAs distributed Bragg reflectors and including an AlAs layer to form a current and waveguiding aperture. The metal contacts are deposited on a topmost p(+) (GaAs)-Ga-. contact layer and on the bottom surface of the n(+)-GaAs substrate. This conventional selectively oxidized top-emitting device configuration avoids the added complexity of fabricating intracavity or coplanar ohmic contacts. The VCSELs operate continuous-wave at room temperature with peak output powers of 0.33 mW and differential slope efficiencies up to 0.23 W/A. The peak lasing wavelengths are near 1.275 mu m, with a sidemode suppression ratio of 28 dB.
A macro model of silicon spiral inductor
(2002-05-01)
Su, CY
;
Chen, LP
;
Chang, SJ
;
Tseng, BM
;
Lin, DC
A new automatic parameter extraction method for modeling Of silicon Spiral inductors is presented. The Concepts on self-resonance frequency (f(sr)) and quality factor of a spiral inductor are utilized to develop the concise extraction procedures. In the mean time, the presented extraction procedures are programmed as a macro to execute all the extractions automatically and shorten the extraction time effectively. Without any additional optimization or curve fitting, almost all the patterns of S-parameters between the measured and the simulation of extracted data implemented with the extraction macro are less than 5%. The programmed extraction macro makes it fast and accurate to extract and characterize the behaviours or silicon-based spiral inductors with different structures and substrate resistivities. It provides a concrete foundation commercial silicon radiofrequency (RF) Circuit design to realizing on-chip silicon RF integrated circuits. Furthermore, the directly extracted equivalent model parameters, without an optimization, also provide a rule to fairly, effectively and phsically judge the performance of a spiral inductor. (C) 2002 Elsevier Science Ltd. All rights reserved.
An anomalous crossover in Vth roll-off for indium-doped nMOSFETs
(2000-09-01)
Chang, SJ
;
Chang, CY
;
Chen, CM
;
Chou, JW
;
Chao, TS
The effects of indium channel implant energy on short-channel effect (SCE) and narrow channel effect (NCE) were studied on NMOS devices down to 0.1 mu m channel length. An anomalous crossover in Vth roll-off curves was observed, for the first time, on indium-implanted splits with different implant energies. This intriguing finding, together with the observed reduction in reverse narrow channel effect (RNCE) and effective channel length with reducing indium implant energy, can be consistently explained by the suppression of transient enhanced diffusion (TED) of channel impurity due to indium deactivation.
An automatic macro program for radio frequency MOSFET characteristics analysis
(2001-10-01)
Su, CY
;
Chang, SJ
;
Chen, LP
;
Ho, YP
;
Huang, GW
The parameter extraction language (PEL) in Agilent IC-CAP software is used to develop an automatic macro program for the analysis of the characteristics of RF MOSFETs. By using this powerful macro program, the time spent on the measurement of the MOSFET characteristics and the related analysis is effectively reduced. This macro program permits a fast and accurate method to obtain the DC and RF characteristics of MOSFETs with different device geometries and operating conditions. It is also suitable for high volume measurements and analyses of MOSFET, and provides a solid jou 71 dation for RF circuit design.
BIST scheme for DAC testing
(2002-07-18)
Chang, SJ
;
Lee, CL
;
Chen, JE
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A low-cost, built-in self-test (BIST) scheme for a digital-to-analogue converter (DAC) is presented. The basic idea is to convert the DAC output voltages corresponding to different input codes into different oscillation frequencies through a voltage controlled oscillator (VCO), and further transfer these frequencies to different digital codes using a counter. According to the input and output codes, performances of a DAC, such as offset error, gain error, differential nonlinearity (DNL), integral nonlinearity (INL), could be effectively detected by simply using digital circuits rather than complex analogue ones. In addition, the annoying DAC output noise could be naturally filtered out by this BIST method.
Characterizations for blends of phosphorus-containing copolyester with poly(ethylene terephthalate)
(1998-09-01)
Chang, SJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
High molecular weight phosphorus-containing copolyesters, poly(ethylene terephthalate)-co-poly(ethylene DDP) (PET-co-PEDDP)s, were prepared and characterized with the objective of producing a non-halogen flame retardant system for practical applications. The phosphorus-containing copolyester with 30 wt% phosphorus (P30 copolyester) was blended with PET to evaluate their characteristics and flame retardancy. Higher phosphorus content results in lower crystallinity and higher char formation after thermal degradation. The rheological behavior remains similar to that of PET. The P30/PET blend possesses higher crystallization rate than the corresponding phosphorus-containing copolyester containing equal phosphorus content. Thermal and rheological behaviors of P30/PET blends are similar to PET or the phosphorus-containing copolyesters. The P30/PET blends are miscible or compatible base on single T(g)s detected by DSC or DMA. The SEM/EDX phosphorus mapping image of the P30/PET blend shows uniform distribution of the phosphorus moieties within the P30/PET matrix, another indication of a compatible or miscible blend between the phosphorus-containing copolyester P30 and PET. Flame retardancy of the P30/PET blend is identical to that of the phosphorus-containing copolyester with identical phosphorus content. Blending of high phosphorus content copolyester with virgin PET provides a feasible method to obtain a flame resistant PET with LOI greater than 28.
Direct oxidation of Si1-xGex layers using Vacuum-Ultra-Violet light radiation in oxygen
(1998-02-01)
Chen, LP
;
Chan, YC
;
Chang, SJ
;
Huang, GW
;
Chang, CY
Oxidation of Si1-xGex films has been carried out by direct photo chemical Vapor deposition (direct photo-CVD) directly with activated O-2 induced by Vacuum-Ultra-Violet (VUV) light radiation, The Auger electron spectroscopy profiles show that no Ge-pileup layer at the oxide/Si1-xGex interface is observed after VUV-induced Si1-xGex oxidation process. The X-ray photoelectron spectroscopy analysis of the samples reveals that Si and Ge are oxidized simultaneously in oxidation process and a mixed oxide layer consisting both SiO2 and GeO2 is formed, This might be the reason that Cc pileup effect is eliminated in this study.
Direct oxidation of Si1-xGex layers using Vacuum-Ultra-Violet light radiation in oxygen
(1998-02-01)
Chen, LP
;
Chan, YC
;
Chang, SJ
;
Huang, GW
;
Chang, CY
Oxidation of Si1-xGex films has been carried out by direct photo chemical Vapor deposition (direct photo-CVD) directly with activated O-2 induced by Vacuum-Ultra-Violet (VUV) light radiation, The Auger electron spectroscopy profiles show that no Ge-pileup layer at the oxide/Si1-xGex interface is observed after VUV-induced Si1-xGex oxidation process. The X-ray photoelectron spectroscopy analysis of the samples reveals that Si and Ge are oxidized simultaneously in oxidation process and a mixed oxide layer consisting both SiO2 and GeO2 is formed, This might be the reason that Cc pileup effect is eliminated in this study.
Effect of coplanar probe pad design on noise figures of 0.35 mu m MOSFETs
(2000-07-20)
Su, CY
;
Chen, LP
;
Chang, SJ
;
Huang, GW
;
Ho, YP
The effects of different coplanar ground-signal-ground (GSG) probe pads on the noise figure characteristics of submicron MOSFETs are presented. Devices with top-level metal as probe pads shielded by grounded bottom-level metal possess the most appropriate probe pad structure for characterising the noise performance of MOSFETs. Equivalent circuits of the probe pads are used to explain the different noise behaviours.
Functional test pattern generation for CMOS operational amplifier
(1997)
Chang, SJ
;
Lee, CL
;
Chen, JE
;
交大名義發表
;
電子工程學系及電子研究所
In this paper, the optimum functional patterns for CMOS operational amplifier are proposed based on an analysis to find the maximum difference between the good circuit and the faulty circuit for a CMOS operational amplifier. The theoretical and simulation results show that the derived test patterns do give the maximum difference at the output even when the circuit has a ''soft'' fault. The results have also been applied to generate test patterns for a programmable gain/loss mixed signal circuit.
High performance 0.1 mu m dynamic threshold MOSFET using indium channel implantation
(2000-03-01)
Chang, SJ
;
Chang, CY
;
Chao, TS
;
Huang, TY
;
電子工程學系及電子研究所
In this letter, we demonstrate a high-performance 0.1 mu m Dynamic Threshold Voltage MOSFET (DTMOS) for ultra-low-voltage (i.e., < 0.7 V) operations. Devices are realized by using super-steep-retrograde indium-channel profile. The steep indium-implanted-channel DTMOS can achieve a large body-effect-factor and a low V-th simutaneously, which results in an excellent performance for the indium-implanted DTMOS.
High-performance and high-reliability 80-nm gate-length DTMOS with indium super steep retrograde channel
(2000-12-01)
Chang, SJ
;
Chang, CY
;
Chen, CM
;
Chao, TS
;
Lee, YJ
In this paper, we demonstrate for the first time a high-performance and high-reliability 80-nm gate-length dynamic threshold voltage MOSFET (DTMOS) using indium super steep retrograde channel implantation. Due to the steep indium super steep retrograde (In-SSR) dopant profile in the channel depletion region, the novel In-SSR DTMOS features a low V-th in the off-state suitable for low-voltage operation and a large body effect to fully exploit the DTMOS advantage simultaneously, which is not possible with conventional DTMOS, As a result, excellent 80-nm gate length transistor characteristics with drive current as high as 348 muA/mum (off-state current 40 nA/mum), a record-high Gm = 1022 mS/mm, and a subthreshold slope of 74 mV/dec, are achieved at 0.7 V operation. Moreover, the reduced body effects that have seriously undermined conventional DTMOS operation in narrow-width devices are alleviated in the In-SSR DTMOS, due to reduced indium dopant segregation. Finally, it was found for the first time that hot-carrier reliability is also improved in DTMOS-mode operation, especially for In-SSR DTMOS.
Impacts of gate structure on dynamic threshold SOI nMOSFETs
(2002-08-01)
Lo, WC
;
Chang, SJ
;
Chang, CY
;
Chao, TS
;
電子工程學系及電子研究所
The effects of different substrate-contact structures (T-gate and H-gate) dynamic threshold voltage silicon-on-insulator (SOI) nMOSFETs (DTMOS) have been investigated. It is found that H-gate structure devices have higher driving current than T-gate under DTMOS-mode operation. This is because H-gate SOI devices have larger body effect factor (gamma), inducing a lager reduction of threshold voltage. Besides, it is found that drain-induced-barrier-lowering (DIBL) is dramatically reduced for both T-gate and H-gate structure devices when devices are operated under DTMOS-mode.
Improvement of high-speed oxide-confined vertical-cavity surface-emitting lasers
(2004-04-01)
Yu, HC
;
Chang, SJ
;
Su, YK
;
Sung, CP
;
Yang, HP
High-speed vertical-cavity surface-emitting lasers that could be modulated up to 10 Giga-bit-per-second (Gbps) were accomplished by using additional proton implantation to reduce the parasitic capacitance. The eye diagram of the implanted device shows a noticeable improvement when compared with those devices without implantation. In contrast to previous reports, moreover, the output power-current-voltage (L-I-V) characteristics of the fabricated devices ill this study show excellent consistency between before and after implantation. The high-temperature lifetime of devices fabricated with a similar process has already exceeded 8100 h up to the present day.
Liquid phase deposited SiO2 on GaN
(2003-04-29)
Wu, HR
;
Lee, KW
;
Nian, TB
;
Chou, DW
;
Wu, JJH
An efficient and low cost approach to deposit uniform silicon dioxide layers on GaN by liquid phase deposition (LPD) near room temperature are described and discussed. The process is simple. GaN wafers are immersed into a H2SiF6 and H3BO3 solution to form the silicon dioxide layers. The deposition conditions and the properties of the SiO2 films will be characterized. (C) 2002 Elsevier Science B.V. All rights reserved.
Numerical analysis of the transient behavior of the sidegating effect in GaAs MESFETs
(1996-07-01)
Chang, SJ
;
Lee, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Transient responses of sidegating effects in GaAs MESFETs are analysed using two-dimensional numerical simulations. Substrates with different trap conditions are considered to clarify the dominant processes in the sidegating transients. Particularly for the electron trap rich substrate (the commonly used undoped semi-insulating GaAs), transient sidegating responses under different bias conditions and the effect of sidegating on the active loads are analyzed to evaluate the effect of sidegating on circuits in operation. Copyright (C) 1996 Elsevier Science Ltd.
Reduced reverse narrow channel effect in thin SOI nMOSFETs
(2000-09-01)
Chang, CY
;
Chang, SJ
;
Chao, TS
;
Wu, SD
;
Huang, TY
The effects of narrow channel width on the threshold voltage of deep submicron silicon-on-insulator (SOI) nMOSFETs with LOGOS isolation have been investigated. The reverse narrow channel effect (RNCE) in SOI devices is found to be dependent on the thickness of the active silicon film. A thinner silicon film is found to depict less threshold voltage fall-off. These results can be explained by a reduced oxide/silicon interface area in the transistor width direction, thus the boron segregation due to silicon interstitials with high recombination rate is reduced.
Sequential distribution of copolyesters containing the phosphorus linking pendant groups characterized by H-1-NMR
(1998-06-01)
Chang, SJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A series of phosphorus-containing copolyesters were synthesized by polycondensation of terephthalic acid (TPA), ethylene glycol (EG) and 9,10-dihydro-10-[2, 3-di(hydroxycarbonyl)propyl]-9-oxa-10-phosphaphenanthrene-10 -oxide (DDP). Chemical structures of these phosphorus-containing copolyesters were characterized by H-1-n.m.r.. Experimental results show that these methylene protons of the ethylene glycol unit resonate at lower field than those of the DDP aliphatic protons. The resonance intensity of DDP aliphatic protons increases with the increase of the phosphorus content. The H-1-n.m.r. spectrum of the DDP aliphatic protons contain three peaks since the proton in H-C-P has greater coupling constant than that of H-C-C. The chemical shifts of these methylene protons in the ethylene glycol unit vary with different sequences. The methylene protons in the ethylene glycol of the T-E-T unit resonate at lower field than those of P-E-T(T-E-P) and P-E-P units. The monomer molar fraction, sequential distribution and degree of randomness of the phosphorus-containing copolyester were determined through analyses of the resonances of methylene protons in the ethylene glycol unit. The molar fractions of the DDP comonomer determined by n.m.r. analyses are close to the charged values in synthetic step and the values determined by an UV method. Moreover, the copolyesters were found to be as random copolymers with a degree of randomness equal to about 1. (C) 1998 Elsevier Science Ltd. All rights reserved.
Sequential distribution of main chain phosphorous-containing copolyesters characterized by H-1 NMR
(1998-01-01)
Chang, SJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A series of main chain phosphorus-containing copolyesters were synthesized by polycondensation of terephthalic acid (TPA), ethylene glycol (EG) and phenyl phosphonic acid (PPA). Chemical structures of these main chain phosphorus-containing copolyesters were characterized by H-1 NMR. Experimental results show that the resonance intensity of PPA aromatic protons increases with increase of the phosphorus content. The chemical shifts of the ethylene protons in the ethylene glycol units vary with different sequences. The resonance chemical shift of the ethylene protons of the T-E-T unit is higher than those of P-E-T (T-E-P) and P-E-P units. The monomer molar fraction, sequential distribution and degree of randomness of the phosphorus-containing copolyesters were determined through analyses of the ethylene protons in the ethylene glycol units. The molar fractions of the PPA comonomer determined by H-1 NMR analyses are close to the values determined by a UV method. The degree of randomness for the copolyesters was found to be in the range 0.66-0.83. (C) 1998 SCI.
Sequential distribution of main chain phosphorous-containing copolyesters characterized by H-1 NMR
(1998-01-01)
Chang, SJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A series of main chain phosphorus-containing copolyesters were synthesized by polycondensation of terephthalic acid (TPA), ethylene glycol (EG) and phenyl phosphonic acid (PPA). Chemical structures of these main chain phosphorus-containing copolyesters were characterized by H-1 NMR. Experimental results show that the resonance intensity of PPA aromatic protons increases with increase of the phosphorus content. The chemical shifts of the ethylene protons in the ethylene glycol units vary with different sequences. The resonance chemical shift of the ethylene protons of the T-E-T unit is higher than those of P-E-T (T-E-P) and P-E-P units. The monomer molar fraction, sequential distribution and degree of randomness of the phosphorus-containing copolyesters were determined through analyses of the ethylene protons in the ethylene glycol units. The molar fractions of the PPA comonomer determined by H-1 NMR analyses are close to the values determined by a UV method. The degree of randomness for the copolyesters was found to be in the range 0.66-0.83. (C) 1998 SCI.