Browsing by Issue Date, starting with "1997-10-15"

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寒梅著花了
(1997-10-15)
管管
Spontaneous emission factor versus cavity volume in low dimensional photonic micro-cavities
(1997-10-15)
Cheng, PH
;
Lee, TD
;
Pan, JS
;
Lai, Y
;
Tai, K
Micro-ring and micro-disk lasers an formed at the same time by transferring the epitaxial layers of 1.55 mu m wavelength InGaAs/ZnGaAsP quantum wells on a glass substrate. The spontaneous emission factor beta in such micro-rings of 5 mu m diameter and 0.2 x 0.5 mu m(2) cross-section is 0.16, which is four times that in micro-disk lasers of the same diameter. The result confirms for the first time that the micro-ring being a lower dimensional photonic system has a larger beta. Study of beta versus the cavity size indicates that the observed spontaneous emission factor is approximately the reciprocal of the normalized cavity volume, when normalization is done to the cubic of the wavelength in the medium. (C) 1997 Elsevier Science B.V.
Simulation and analysis of the capacitance-voltage characteristics of the delta-doped semiconductors
(1997-10-15)
Liu, DG
;
Lee, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, a self-consistent model to simulate the general characteristics of one-dimensional semiconductor structures is demonstrated. During calculation, possible quantum effects and the distributions of both electrons and holes are all considered. In this model, a continuity equation is solved to calculate the distribution of free electrons and holes, The possible quantum wells are sought using the Schrodinger equation. The overall charge density and potential are obtained self-consistently by an iteration scheme. The C-V characteristics of the delta-doped structures are simulated and then compared with those of practical samples. By comparing with these delta-doped samples, the effective numbers of dopant atoms can be precisely determined. For these highly doped samples, it is found that the activation rates are only about half. This finding can be verified by Hall measurements which confirms the accuracy in this study. (C) 1997 Elsevier Science S.A.
On upper bounds for the pseudo-achromatic index
(1997-10-15)
Chiang, NP
;
Fu, HL
;
應用數學系
;
Department of Applied Mathematics
In this paper, we give another approach to the pseudo-achromatic index and the achromatic index of a graph and study upper bounds for them. We have obtained the following best possible upper bounds: (i) Psi'(G)less than or equal to Psi(S)'(G)less than or equal to right perpendicular(e(G) + chi'(G))/2left perpendicular; and (ii) Psi'(G)less than or equal to Psi(S)'(G) less than or equal to max(1 less than or equal to k less than or equal to right perpendicularp/2left perpendicular) min{right perpendicularp Delta(G)/2kright perpendicular,2k(Delta(G)-1) + 1}. Using these bounds, the pseudo-achromatic indices of graphs of certain types are obtained which generalize the results of Bouchet (1978), Chiang and Fu (1995), Geller and Kronk (1974) and Jamison (1989) for achromatic indices to pseudo-achromatic indices.
寒梅著花了
(1997-10-15)
管管
寒梅著花了
(1997-10-15)
管管
Anion-terminated zinc-blende CdS(100) surface
(1997-10-15)
Lin, CM
;
Tsai, MH
;
Yang, TJ
;
Chuu, DS
;
電子物理學系
Using the local-orbital density-functional molecular-dynamics method, we have studied the surface structure of the strain-stabilized zinc-blende monolayer anion-terrainated CdS(100) surface. By analogy with the GaAs(100) surface, we have considered four structural models and found that the structure with a (2 x 4) unit cell, in which there are a two-dimer unit and a two-shifted-dimer unit, is the most favorable. These results can be understood in terms of physical properties associated with ionicity.
寒梅著花了
(1997-10-15)
管管
Spontaneous emission factor versus cavity volume in low dimensional photonic micro-cavities
(1997-10-15)
Cheng, PH
;
Lee, TD
;
Pan, JS
;
Lai, Y
;
Tai, K
Micro-ring and micro-disk lasers an formed at the same time by transferring the epitaxial layers of 1.55 mu m wavelength InGaAs/ZnGaAsP quantum wells on a glass substrate. The spontaneous emission factor beta in such micro-rings of 5 mu m diameter and 0.2 x 0.5 mu m(2) cross-section is 0.16, which is four times that in micro-disk lasers of the same diameter. The result confirms for the first time that the micro-ring being a lower dimensional photonic system has a larger beta. Study of beta versus the cavity size indicates that the observed spontaneous emission factor is approximately the reciprocal of the normalized cavity volume, when normalization is done to the cubic of the wavelength in the medium. (C) 1997 Elsevier Science B.V.
Simulation and analysis of the capacitance-voltage characteristics of the delta-doped semiconductors
(1997-10-15)
Liu, DG
;
Lee, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, a self-consistent model to simulate the general characteristics of one-dimensional semiconductor structures is demonstrated. During calculation, possible quantum effects and the distributions of both electrons and holes are all considered. In this model, a continuity equation is solved to calculate the distribution of free electrons and holes, The possible quantum wells are sought using the Schrodinger equation. The overall charge density and potential are obtained self-consistently by an iteration scheme. The C-V characteristics of the delta-doped structures are simulated and then compared with those of practical samples. By comparing with these delta-doped samples, the effective numbers of dopant atoms can be precisely determined. For these highly doped samples, it is found that the activation rates are only about half. This finding can be verified by Hall measurements which confirms the accuracy in this study. (C) 1997 Elsevier Science S.A.
寒梅著花了
(1997-10-15)
管管
Effects of isolation materials on facet formation for silicon selective epitaxial growth
(1997-10-20)
Tseng, HC
;
Chang, CY
;
Pan, FM
;
Chen, JR
;
Chen, LJ
Effects of isolation materials on facet formation for low temperature Si selective epitaxial growth (SEG) using Si2H6 have been demonstrated by ultrahigh vacuum-chemical molecular epitaxy (UHV-CME) system. The activation energy of the Si epitaxial growth is 47.35 Kcal/mol. The isolation material includes silicon nitride, wet oxide, and tetraethylorthosilicate (TEOS) oxide. Different isolation materials have different faceting behaviors for the Si epilayer. A silicon nitride mask and a wet oxide mask result in a preferred faceting plane of (111) and (311), respectively. Using a TEOS oxide mask, we obtain a low temperature Si SEG layer without facet and twin formation, The preferred faceting plane orientation for different isolation materials is ascribed to the difference in the interface free energy between the Si layer and the isolation material. (C) 1997 American Institute of Physics.
k-path partitions in trees
(1997-10-21)
Yan, JH
;
Chang, GJ
;
Hedetniemi, SM
;
Hedetniemi, ST
;
應用數學系
For a fixed positive integer k, the k-path partition problem is to partition the vertex set of a graph into the smallest number of paths such that each path has at most k vertices. The 2-path partition problem is equivalent to the edge-cover problem. This paper presents a linear-time algorithm for the k-path partition problem in trees. The algorithm is applicable to the problem of finding the minimum number of message originators necessary to broadcast a message to all vertices in a tree network in one or two time units.
Suppression of optical beat interference using synchronised CDMA technique and in-band clipping carrier
(1997-10-23)
Wang, BH
;
Hsiao, CC
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
The authors propose adding a coherent in-band clipping carrier to a previously demonstrated Walsh-code-based synchronised CDMA (S-CDMA) technique to further suppress the optical beat interference (OBI). Experimental results showed thar a negligible system power penalty can be achieved even when the OBI-induced intensity noise was as high as -90.9dB/Hz. In addition, a large system dynamic range of 10dB can tx obtained to relax the tight power control requirement on S-CDMA signals.
Dielectric characteristics of doped Ba1-xSrxTiO3 at the paraelectric state
(1997-10-30)
Liou, JW
;
Chiou, BS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Ba1-xSrxTiO3 (x=0 to 1) ferroelectric ceramics doped with 1.0 mol.% MgO and 0.05 mol.% MnO2 were prepared with a rate-controlled sintering profile. The lattice constant of this BST system decreases as the strontium molar fraction increases. This is due to the smaller Sr2+ ionic radius than that of Ba2+. The temperature dependence of the dielectric constant is measured at 10 kHz. A linear relation of the Curie temperature of the BST system to the Sr fraction for x less than or equal to 0.75 is observed. When this reaction is fitted to a modified Curie-Weiss law, two parameters, the critical exponent and the diffuseness parameter, which represent the order of transition broadening, can be calculated. From the values of these two parameters, it is suggested that the physical meanings of these two parameters are correlated to each other. The transition broadening is greatest for x = 0.5 owing to the most composition fluctuation. Dipole relaxation of the composition with x = 0.25 is observed at frequencies above 1 MHz. On the basis of Cole-Cole analysis, a low frequency relaxation due to dopants Mn4+ at below 50 kHz is observed. (C) 1997 Elsevier Science S.A.
Chemical mechanical polishing for selective CVD-W
(1997-10-30)
Wang, MT
;
Yeh, WK
;
Tsai, MS
;
Tseng, WT
;
Chang, TC
This work investigates chemical mechanical polishing (CMP) for W-filled contact holes, vias, and trenches by selective chemical vapor deposition. A novel process that combines the CMP technique with selective chemical vapor deposition of tungsten (CVD-W) was employed to remove nail heads due to overgrowth and W-particles on the surface of dielectric due to selectivity loss. The overfilled nail heads and the selectivity loss can be completely removed with very low down-pressure (3 psi) in a very short polishing time (30 s). This indicates that the novel process is very promising for ULSI multilevel interconnection application. The removal rate selectivities of W to thermal oxide, PECVD-TEOS, and BPSG were found to be 47:1, 30:1 and 15:1, respectively, while the selectivities of W to the barrier metals of TiW, Ti and Ta were determined to be 0.6:1, 6:1 and 28:1, respectively. (C) 1997 Elsevier Science S.A.
Chemical mechanical polishing for selective CVD-W
(1997-10-30)
Wang, MT
;
Yeh, WK
;
Tsai, MS
;
Tseng, WT
;
Chang, TC
This work investigates chemical mechanical polishing (CMP) for W-filled contact holes, vias, and trenches by selective chemical vapor deposition. A novel process that combines the CMP technique with selective chemical vapor deposition of tungsten (CVD-W) was employed to remove nail heads due to overgrowth and W-particles on the surface of dielectric due to selectivity loss. The overfilled nail heads and the selectivity loss can be completely removed with very low down-pressure (3 psi) in a very short polishing time (30 s). This indicates that the novel process is very promising for ULSI multilevel interconnection application. The removal rate selectivities of W to thermal oxide, PECVD-TEOS, and BPSG were found to be 47:1, 30:1 and 15:1, respectively, while the selectivities of W to the barrier metals of TiW, Ti and Ta were determined to be 0.6:1, 6:1 and 28:1, respectively. (C) 1997 Elsevier Science S.A.
Effects of corrosion environments on the surface finishing of copper chemical mechanical polishing
(1997-10-31)
Wang, MT
;
Tsai, MS
;
Liu, C
;
Tseng, WT
;
Chang, TC
Copper chemical mechanical polishing (Cu-CMP) was investigated using slurries containing alumina abrasive and various types and concentrations of oxidizer, as well as benezotriazole (BTA) additive. We found that the corrosion rate of copper film decreases with increasing BTA concentration in 3 vol.% HNO3 solution, but the passivation effect of BTA saturates as the concentration reaches about 0.01 M. On the other hand, a small amount of H2O2 in H2O2/XJFW8099 slurry enhances the corrosion rate dramatically, while abundance of H2O2 in the slurry suppresses the corrosion reaction effectively. The polishing rate and its non-uniformity decrease with increasing volume ratio of H2O2 in H2O2/XJEW8099 slurry. A very smooth surface with a removal rate of 363.0 nm/min was obtained using the slurry of 1/1 ratio. Depletion of H2O2 in the slurry can result in more abrasive residuals as well as a rougher surface; the surface roughness increases from 0.3 to 9.9 nm as the H2O2/XJFW8099 ratio decreases from 1/1 to 1/4. Our results indicate that the corrosion rate, polishing rate and surface roughness of copper films are sensitively dependent on the type and concentration of oxidizer as well as the BTA additive. (C) 1997 Elsevier Science S.A.
Stabilizing dielectric constant of fluorine-doped SiO2 film by N2O and NH3 plasma post-treatment
(1997-10-31)
Mei, YJ
;
Chang, TC
;
Chang, SJ
;
Pan, FM
;
Chen, MSK
Fluorine doped oxide (SiO2-xFx) films have been found to exhibit a low dielectric constant. However, the critical issue about SiO2-xFx is its low resistance to moisture which causes the dielectric constant of the film to increase with time. In this work, N2O and NH3 plasma post treatments are applied to as-deposited SiO2-xFx films. It has been observed that NH3 plasma post-treatments of SiO2-xFx are quite efficient at blocking moisture. The dielectric constant and stress values of the SiO2-xFx films after the N2O and NH3 plasma post-treatments are very stable. The disadvantage of N2O plasma post-treatment is that the dielectric constant of the SiO2-xFx film increases from 3.21 to 3.6 due to fluorine desorption from the SiO2-xFx network. On the other hand, NH3 plasma post-treatment is more efficient at blocking moisture and keeping the low dielectric constant unchanged due to surface nitridation of the SiO2-xFx film. (C) 1997 Elsevier Science S.A.
Preparation of a novel target material for carbon nitride film deposition
(1997-10-31)
Lu, TR
;
Kuo, CT
;
Chen, TM
;
材料科學與工程學系
;
應用化學系
To increase the nitrogen content and the degree of crystallinity in carbon nitride films by film deposition techniques (i.e. sputtering, laser ablation etc.), a novel target material composed of carbon nitride has been prepared by UV photo-assisted synthesis. The intention is to replace the traditional graphite target with this material. This synthesis involves photo-chemical reaction of sodium amide and chloroform as carbon and nitrogen sources, respectively, followed by high temperature sintering under flowing nitrogen. Elemental analyses indicate the presence of C, N and H in the target material with a nitrogen to carbon ratio of 0.23. Infrared spectroscopy shows a mixture of sp(3) and sp(2) carbon and sp(2) nitrogen in the sintered powder. Six diffraction peaks attributable to alpha-C3N4 were observed in XRD pattern. Grains of similar to 0.3 pm in diameter in an extended network were also observed in the SEM micrographs. The sintered carbon nitride powder is stable up to 800 degrees C. (C) 1997 Elsevier Science S.A.