Browsing by Author "Sze, SM"

Now showing 1 - 20 of 71

1.55-mu m and infrared-band photoresponsivity of a Schottky barrier porous silicon photodetector
(2001-02-01)
Lee, MK
;
Chu, CH
;
Wang, YH
;
Sze, SM
;
電子工程學系及電子研究所
We have investigated the spectral responsivity of porous silicon Schottky barrier photodetectors in the wavelength range 0.4-1.7 mum The photodetectors show strong photoresponsivity in both the visible and the infrared bands, especially at 1.55 mum. The photocurrent can reach 1.8 mA at a reverse bias of 6 V under illumination by a 1.55-mum, 10-mW laser diode. The corresponding quantum efficiency is 14.4%. (C) 2001 Optical Society of America.
A computational efficient method for HBT intermodulation distortions and two-tone characteristics simulation
(2001)
Huang, KY
;
Li, YM
;
Lee, CP
;
Sze, SM
;
電子工程學系及電子研究所
In this paper, a new simulation method for two-tone characteristics calculations and the third-order intercept point (OIP3) of heterojunction bipolar transistor (HBT) in large-scale time domain is proposed. Base on waveform relaxation (WR) and monotone iterative (MI) methods, we solve a set of nonlinear ordinary differential equation (ODE) of equivalent circuit. With this approach, the two-tone characteristics in frequency domain for HBTs were directly computed from time domain result with fast Fourier transform (FFT). Simulation results on a realistic HBT are presented to show the accuracy and efficiency of the method.
A computational method for energy level spin splitting simulation in InAs/GaAs semiconductor quantum dots
(2002-05-01)
Li, YM
;
Voskoboynikov, O
;
Lee, CP
;
Sze, SM
;
Tretyak, O
An impact of the spin-orbit interaction on the electron quantum confinement is considered theoretically for narrow gap semiconductor cylindrical quantum dots. To study the phenomena for InAs quantum dot embedded into GaAs semiconductor matrix, the effective one electronic band Hamiltonian, the energy position dependent electron effective mass approximation, and the spin-dependent Ben Daniel-Duke boundary conditions axe considered, formulated and solved numerically. To solve the nonlinear Schrodinger equation, we propose a nonlinear iterative algorithm. This calculation algorithm not only converges for all simulation cases but also has a good convergent rate. With the developed quantum dot simulator, we study the effect of the spin-orbit interaction for narrow gap InAs/GaAs semiconductor cylindrical quantum dots. From the numerical calculations, it has been observed that the spin-orbit interaction leads to a sizeable spin-splitting of the electron energy states with nonzero angular momentum. Numerical evidence is presented to show the splitting result is strongly dependent on the quantum dot size.
A distributed charge storage with GeO2 nanodots
(2004-04-05)
Chang, TC
;
Yan, ST
;
Hsu, CH
;
Tang, MT
;
Lee, JF
In this study, a distributed charge storage with GeO2 nanodots is demonstrated. The mean size and aerial density of the nanodots embedded in SiO2 are estimated to be about 5.5 nm and 4.3x10(11) cm(-2), respectively. The composition of the dots is also confirmed to be GeO2 by x-ray absorption near-edge structure analyses. A significant memory effect is observed through the electrical measurements. Under the low voltage operation of 5 V, the memory window is estimated to similar to0.45 V. Also, a physical model is proposed to demonstrate the charge storage effect through the interfacial traps of GeO2 nanodots. (C) 2004 American Institute of Physics.
A domain partition approach to parallel adaptive simulation of dynamic threshold voltage MOSFET
(2002-08-01)
Li, YM
;
Chao, TS
;
Sze, SM
;
電子工程學系及電子研究所
;
友訊交大聯合研發中心
In this paper, we present a dynamic domain partition simulation technique for parallel numerical solutions of semiconductor device equations. Based on the adaptive finite volume method, a posteriori error estimation, and monotone iterative algorithm, this dynamic load balancing approach has been successfully developed and implemented on a Linux cluster with message passing interface library. The developed simulator is then applied to calculate the physical characteristics of deep submicron dynamic threshold voltage MOSFET (DTMOS). We simulate DTMOS with two different parallel algorithms: (1) 2D dynamic load balancing for parallel domain decomposition; (2) parallel I-V point simulation. Benchmark results show that a well-designed load balancing simulation can reduce the execution time up to an order of magnitude. Compared with the measured data, the simulated results for a 0.08 mum DTMOS are demonstrated to show the accuracy and efficiency of the method. (C) 2002 Elsevier Science B.V All rights reserved.
A method for fabricating a superior oxide/nitride/oxide gate stack
(2004)
Chang, TC
;
Yan, ST
;
Liu, PT
;
Wang, MC
;
Sze, SM
A superior oxide/nitride/oxide (ONO) gate stack was demonstrated. High density plasma chemical vapor deposition was used to deposit the silicon nitride layer instead of the conventional low-pressure chemical vapor deposition for silicon/oxide/nitride/oxide/silicon technology. The densified nitride layer was performed by high-temperature dry oxidation to form a thermally grown blocking oxide layer on the silicon nitride rather than a deposited oxide layer. The ONO gate stack shows large memory window, high breakdown voltage, and reliable endurance characteristics, which is a potential candidate for future nonvolatile memory technology. (C) 2004 The Electrochemical Society.
A new parallel adaptive finite volume method for the numerical simulation of semiconductor devices
(2001-12-15)
Li, YM
;
Liu, JL
;
Chao, TS
;
Sze, SM
;
應用數學系
Based on adaptive finite volume approximation, a posteriori error estimation, and monotone iteration, a novel system is proposed for parallel simulations of semiconductor devices. The system has two distinct parallel algorithms to perform a complete set of I-V simulations for any specific device model. The first algorithm is a domain decomposition on I-irregular unstructured meshes whereas the second is a parallelization of multiple I-V points. Implemented on a Linux cluster using message passing interface libraries, both algorithms are shown to have excellent balances on dynamic loading and hence result in efficient speedup. Compared with measurement data, computational results of sub-micron MOSFET devices are given to demonstrate the accuracy and efficiency of the system. (C) 2001 Elsevier Science B.V. All rights reserved.
A novel approach of fabricating germanium nanocrystals for nonvolatile memory application
(2004-01-01)
Chang, TC
;
Yan, ST
;
Liu, PT
;
Chen, CW
;
Lin, SH
A nonvolatile memory device embedded with Ge nanocrystal dots is fabricated by the thermal oxidation of Si0.8Ge0.2 combined with a rapid thermal annealing at 950degreesC in N-2 gas. The tunnel oxide in the nonvolatile memory is controlled to be 4.5 nm thick and embedded with 5.5 nm Ge nanocrystals. A low operating voltage, 5 V, is implemented and a significant threshold-voltage shift, 0.42 V, is observed. When the electrons are trapped in the Ge nanocrystals, the effect of Coulomb blockade prevents the injection and storage of more electrons and decreases the leakage current. Also, the retention characteristics are tested to be robust. (C) 2003 The Electrochemical Society.
A novel distributed charge storage element fabricated by the oxidation of amorphous silicon carbide
(2004)
Chang, TC
;
Yan, ST
;
Chen, YT
;
Liu, PT
;
Sze, SM
A novel distributed charge storage element fabricated by the oxidation of amorphous silicon carbide is proposed. For low-temperature oxidation processes, the oxidized SiCO gate stack shows a larger memory window due to the retainable dangling bonds with more Si-C bonding types and less Si-O bonds. Under 5 V write operation of the low-temperature oxidized SiCO stack, a 1.5 V threshold voltage shift is exhibited, which is sufficient for a memory device to define "0'' and "1.'' Also, the low-temperature oxidation process of the SiCO layer saves the thermal budget for the manufacturing processes of nonvolatile memory devices. (C) 2004 The Electrochemical Society.
A practical implementation of parallel dynamic load balancing for adaptive computing in VLSI device simulation
(2002)
Li, Y
;
Sze, SM
;
Chao, TS
;
電子工程學系及電子研究所
;
友訊交大聯合研發中心
We present a new parallel semiconductor device simulation using the dynamic load balancing approach. This semiconductor device simulation based on the adaptive finite volume method with a posteriori error estimation has been developed and successfully implemented on a 16-PC Linux cluster with a message passing interface library. A constructive monotone iterative technique is also applied for solution of the system of nonlinear algebraic equations. Two different parallel versions of the algorithm to perform a complete device simulation are proposed. The first is a dynamic parallel domain decomposition approach, and the second is a parallel current-voltage characteristic points simulation. This implementation shows that a well-designed load balancing simulation can significantly reduce the execution time up to an order of magnitude. Compared with the measured data, numerical results on various submicron VLSI devices are presented, to show the accuracy and efficiency of the method.
Ambipolar Schottky-barrier TFTs
(2002-02-01)
Lin, HC
;
Yeh, KL
;
Huang, TY
;
Huang, RG
;
Sze, SM
A novel Schottky-barrier metal-oxide-semiconductor thin-film transistor (SBTFT) was successfully demonstrated and characterized. The new SBTFT device features a fleld-induced-drain (FID) region, which is controlled by a metal field-plate lying on top of the passivation oxide. The FED region is sandwiched between the silicided drain and the active channel region. Carrier types and the conductivity of the transistor are controlled by the metal field-plate. The device is thus capable of ambipolar operation. Excellent ambipolar performance with on/off current ratios over 10(6) for both p- and n-channel operations was realized simultaneously on the same device fabricated with polysilicon active layer. Moreover, the off-state leakage current shows very weak dependence on the gate-to-drain voltage difference with the FID structure. Finally, the effects of FED length are explored.
Application of field-induced source/drain Schottky metal-oxide-semiconductor to fin-like body field-effect transistor
(2002-06-01)
Lin, HC
;
Wang, MF
;
Hou, FJ
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Liu, JT
;
Huang, TY
A novel Schottky barrier silicon-on-insulator (SOI) metal-oxide-semiconductor field effect transistor (MOSFET) device was proposed and demonstrated, The new device features a silicide source/drain and field-induced source/drain (S/D) extensions. Excellent ambipolar performance with a near-ideal sub-threshold slope (similar to 60 mV/decade) and high on-/off-state current ratio (comparable to or higher than 10(9)) is realized, for the first time, on a single device. These encouraging results suggest that the new device may be suitable for some niche applications requiring simple and low-temperature processing of complementary metal-oxide-semiconductor(CMOS)-like devices.
Calculation of induced electron states in three-dimensional semiconductor artificial molecules
(2002-08-01)
Li, YM
;
Voskoboynikov, O
;
Lee, CP
;
Sze, SM
;
友訊交大聯合研發中心
The energy levels calculation of electrons confined in small three-dimensional (3D) coupled quantum InxGa1-xAs dots embedded in GaAs semiconductor matrix is presented. The quantum dots have disk shapes and are separated (in the disk symmetry axis direction) by a certain distance. Based on the effective one electronic band Hamiltonian, the energy and position dependent electron effective mass approximation, a finite height hard-wall 3D confinement potential, and the Ben Daniel-Duke boundary conditions, the problem is formulated and solved for the disk-shaped coupled quantum dots. To calculate the ground and induced state energy levels, the nonlinear 3D Schrodinger equation (SE) is solved with a developed nonlinear iterative method to obtain the final self-consistent solutions. In the iteration loops, the Schrodinger equation is discretized with a nonuniform mesh finite difference method, and the matrix eigenvalue problem is solved with the balanced and shifted QR method. Our complete 3D approach demonstrates a principal possibility that the number of bound electronic states in the system can be changed when the interdot (vertical) distance is modified. However, it is impossible to produce an additional possibility to manipulate the system electronic properties within only a two-dimensional (2D) simulation. (C) 2002 Elsevier Science B.V. All rights reserved.
Characterization of NH3 plasma-treated Ba0.7Sr0.3TiO3 thin films
(2000-04-01)
Wuu, DS
;
Horng, RH
;
Liao, FC
;
Leu, CC
;
Huang, TY
The effects of plasma surface treatment, using NH3 gas, of Ba0.7Sr0.3TiO3 (BST) films on the leakage and dielectric characteristics of a Pt/BST/Pt capacitor were investigated. As a result of the exposure of BST to the plasma, the leakage current density of the BST capacitor can be improved by three orders of magnitude as compared to that of the nonplasma-treated sample at an applied voltage of 1.5 V. Nevertheless, the surface morphology of BST was also changed by the NH3 plasma, as explored by atomic force microscopy. From the X-ray photoelectron spectroscopy examination, the existence of the N 1 s peak was observed in the plasma-treated sample. It induces the additional space charge and results in the reduction of the dielectric constant. (C) 2000 Elsevier Science Ltd. All rights reserved.
Characterization of porous silicate for ultra-low k dielectric application
(2002-07-01)
Liu, PT
;
Chang, TC
;
Hsu, KC
;
Tseng, TY
;
Chen, LM
Thermal stability of a porous low-k film is a critical issue for application consideration in the back-end-of-line. In this study, thermal stability of the porous silicate has been investigated by changing the thermal processing temperatures. Experimental results have shown that the dielectric constant of the porous silicate still remains below 2.0 after thermal processing at 500 degreesC for I h. A series of material analysis techniques and electrical characteristics have been used to verify the physical and chemical characteristics of the porous silicate film. (C) 2002 Elsevier Science B.V. All rights reserved.
Computer simulation of electron energy levels for different shape InAs/GaAs semiconductor quantum dots
(2001-11-15)
Li, YM
;
Voskoboynikov, O
;
Lee, CP
;
Sze, SM
;
電子工程學系及電子研究所
A computational technique for the energy levels calculation of an electron confined by a 3D InAs quantum dot (QD) embedded in GaAs semiconductor matrix is presented. Based on the effective one electronic band Hamiltonian, the energy and position dependent electron effective mass approximation, a finite height hard-wall 3D confinement potential, and the Ben Daniel-Duke boundary conditions, the problem is formulated and solved for the disk, ellipsoid, and conical-shaped InAs/GaAs QDs. To calculate the ground state and first excited state energy levels, the nonlinear 3D Schrodinger is solved with a developed nonlinear iterative algorithm to obtain the final self-consistent solutions. In the iteration loops, the Schrodinger equation is discretized with a nonuniform mesh finite difference method, and the corresponding matrix eigenvalue problem is solved with the balanced and shifted QR method. The proposed computational method has a monotonically convergent property for all simulation cases. The computed results show that for different quantum dot shapes, the parabolic band approximation is applicable only for relatively large dot volume. For the first excited states the non-parabolicity effect also has been found to be stronger than it at ground state. The QD model and numerical method presented here provide a novel way to calculate the energy levels of QD and it is also useful to clarify principal dependencies of QD energy states on material band parameter and QDs size for various QD shapes. (C) 2001 Elsevier Science B.V. All rights reserved.
Dependence of energy gap on magnetic field in semiconductor nano-scale quantum rings
(2003-06-10)
Li, YM
;
Lu, HM
;
Voskoboynikov, O
;
Lee, CP
;
Sze, SM
We study the electron and hole energy states for a complete three-dimensional (3D) model of semiconductor nanoscale quantum rings in an external magnetic field. In this study, the model formulation includes: (i) the position dependent effective mass Hamiltonian in non-parabolic approximation for electrons, (ii) the position dependent effective mass Hamiltonian in parabolic approximation for holes, (iii) the finite hard wall confinement potential, and (iv) the Ben Daniel-Duke boundary conditions. To solve this 3D non-linear problem, we apply the non-linear iterative method to obtain self-consistent solutions. We find a non-periodical oscillation of the energy band gap between the lowest electron and hole states as a function of external magnetic fields. The result is useful in describing magneto-optical properties of the nano-scale quantum rings. (C) 2003 Elsevier Science B.V. All rights reserved.
Dielectric characteristics of low-permittivity silicate using electron beam direct patterning for intermetal dielectric applications
(2003-11-17)
Liu, PT
;
Chang, TC
;
Tsai, TM
;
Lin, ZW
;
Chen, CW
A direct patterning technology of low-permittivity silicate-based polymer is investigated with electron-beam lithography for multilevel interconnections. The smallest feature size of 60 nm for damascene lines can be directly patterned in the silicate film. In this direct patterning, dielectric regions exposed by electron beam are crosslinked and form desirable patterns, while the others are dissolvable in an aqueous solution containing 2.38% tetramethylammonium hydroxide. With an optimum condition of electron-beam lithography, the electron-beam-irradiated silicate exhibits superior dielectric properties than that of the furnace-cured silicate film, due to minimizing the break of Si-H bonds and moisture uptake. The explanation is in agreement with the analyses of Fourier transform infrared spectroscopy and thermal desorption spectroscopy. (C) 2003 American Institute of Physics.
Effect of shape and size on electron transition energies of InAs semiconductor quantum dots
(2002-04-01)
Li, YM
;
Voskoboynikov, O
;
Lee, CP
;
Sze, SM
;
Tretyak, O
We present a theoretical study of the electron energy states in three-dimensional narrow gap semiconductor quantum (Jots with different shapes under an external magnetic field. The problem is solved by using the effective one-electronic-band Hamiltonian, the energy- and position-dependent electron effective mass approximation and the Ben Daniel-Duke boundary condition. We investigate small InAs/GaAs quantum dots with disk, lenticular, and conical shapes. Electron energy dependence on volume is expressed as V-gamma where the exponent gamma depends on the dot shapes and can vary over a wide range. The most stable against the dot size deviations (among dots of the same base radius) is the energy spectra of the conical dots. In addition, this type of dot also has the weakest diamagnetic shift. Contrarily, quantum dots with cylindrical shapes show a wide deviation in energy and a relatively strong diamagnetic shift.
Effective repair to ultra-low-k dielectric material (k-2.0) by hexamethyidisilazane treatment
(2002-07-01)
Mor, YS
;
Chang, TC
;
Liu, PT
;
Tsai, TM
;
Chen, CW
O-2 plasma ashing is commonly used to remove photoresist. The effect of O-2 plasma ashing on the porous organosilicate glass (CH3SiO1.5)(n), one of the spin-on materials, is investigated. O2 plasma can oxidize the methyl groups in porous organosilicate glass (POSG), which leads to the formation of Si-OH groups. The hydrophilic Si-OH groups will induce moisture uptake so that electrical degradation will occur in POSG film. Pure hexamethyldisilazane (HMDS) vapor (100% HMDS) can react with the Si-OH groups in POSG film. It converts hydrophilic Si-OH groups into hydrophobic Si-O-Si(CH3)(3) groups against moisture uptake. The leakage current density decreases by a factor of 2-3 and the dielectric constant decreases from 3.62 to 2.4 when O-2 plasma-damaged POSG undergoes HMDS treatment at 80degreesC for 15 min. Therefore, HMDS treatment is the effective technique to repair the electrical degradation to POSG film during photoresist stripping processing. (C) 2002 American Vacuum Society.