Browsing by Author "Chang, SW"

Now showing 1 - 9 of 9

A gold-free fully copper-metallized InP heterojunction bipolar transistor using non-alloyed ohmic contact and platinum diffusion barrier
(2005)
Chang, SW
;
Chang, EY
;
Lee, CS
;
Chen, KS
;
Tseng, CW
A gold-free, fully Cu-metallized InP heterojunction bipolar transistor using non-alloyed Ti/Pt/Cu and Pt/Ti/Pt/Cu ohmic contacts and platinum diffusion barrier has been successfully fabricated. The InGaAs/Ti/Pt/Cu ohmic structure was stable after annealing up to 350 degrees C as judged from the Auger depth profiles. A current-accelerated stress test was conducted on the device with a current density J(C) = 80kA/cm(2) for 24h, and the current gain showed no degradation after the current stress. The devices were also thermally annealed at 200 degrees C for 3 h and showed almost no change in the electrical parameters after the heat treatment. The results show that the Au-free, fully Cu-metallized InP heterojunction bipolar transistor (HBT) can be realized using non-alloyed ohmic contacts and Pt diffusion barrier.
Comparative studies on field emission properties of carbon-based materials
(2000-04-01)
Chen, KH
;
Wu, JJ
;
Chen, LC
;
Wen, CY
;
Kichambare, PD
Comparative studies on field emission properties of various carbon-related materials including diamond, amorphous carbon, SiCN films, SiCN nanorods, and carbon nanotubes are presented. While diamond is well known for its potential use in cold cathodes, the emission current of a hydrogen-treated diamond film is relatively small compared to that of amorphous carbon or diamond-like-carbon film. Meanwhile, carbon nanotubes have demonstrated large emission currents at much lower threshold voltages, showing their potential for applications. However, the emission from carbon nanotubes is subjected to significant decay under long-term operation. The emission current and long-term stability can be improved using a new SiCN compound with nanorod morphology. The effective barrier height and the held enhancement factor derived from the Fowler-Nordheim equation are discussed in this paper. (C) 2000 Elsevier Science S.A. All rights reserved.
Field emission from quasi-aligned SiCN nanorods
(2000-05-01)
Tarntair, FG
;
Wen, CY
;
Chen, LC
;
Wu, JJ
;
Chen, KH
We report on the preparation and field emission properties of quasi-aligned silicon carbon nitride (SiCN) nanorods. The SiCN nanorods are formed by using a two-stage growth method wherein the first stage involves formation of a buffer layer containing high density of nanocrystals by electron cyclotron resonance plasma enhanced chemical vapor deposition and the second stage involves using microwave plasma enhanced chemical vapor deposition for high growth rate along a preferred orientation. It should be noted that growth of the SiCN nanorods is self-mediated without the addition of any metal catalyst. Scanning electron microscopy shows that the SiCN nanorods are six-side-rod-shaped single crystals of about 1-1.5 mu m in length and about 20-50 nm in diameter. Energy dispersive x-ray spectrometry shows that the nanorod contains about 26 at. % of Si, 50 at. % of C, and 24 at. % of N. Characteristic current-voltage measurements indicate a low turn-on field of 10 V/mu m. Field emission current density in excess of 4.5 mA/cm(2) has been observed at 36.7 V/mu m. Moreover, SiCN nanorods exhibited rather stable emission current under constant applied voltage. (C) 2000 American Institute of Physics. [S0003-6951(00)01117-7].
Gold-free fully cu-metallized InGaP/GaAs heterojunction bipolar transistor
(2005-01-01)
Chang, SW
;
Chang, EY
;
Biswas, D
;
Lee, CS
;
Chen, KS
A gold-free, fully Cu-metallized InGaP/GaAs heterejunction bipolar transistor using platinum as the diffusion barrier has been successfully fabricated. The HBT uses Pd/Ge and Pt/Ti/Pt/Cu for n-type and p(+)-type ohmic contacts, respectively, and Ti/Pt/Cu for interconnect metals with platinum as the diffusion barrier. The Ti/Pt/Cu structure was stable during annealing up to 350degreesC judging from the X-ray diffraction (XRD) data and sheet resistance. A current-accelerated stress test was conducted on the device with a current density J(C) = 140 kA/cm(2) for 24 h, and the current gain showed no degradation. The devices were also thermally annealed at 250degreesC,for 24 h and showed little change. We have successfully demonstrated that an Au-free, fully Cu-metallized HBT can be realized using Pt as the diffusion barrier and Pd/Ge and Pt/Ti/Pt/Cu as the ohmic contacts.
Polarized blue emission based on a side chain liquid crystalline polyacrylate containing bis-tolane side groups
(2002-03-01)
Chang, SW
;
Li, AK
;
Liao, CW
;
Hsu, CS
;
應用化學系
A novel side chain liquid crystalline (LC) polyacrylate (1P) containing highly conjugated bis-tolane side groups was synthesized and used for polymer light emitting diodes application. Polymer 1P shows a nematic phase at room temperature. It exhibits a UV absorption peak at 330 run and emits a blue light at 425 inn. Polyimide (PI), polyaniline (PA) and poly(3,4-diethylenedioxythiophene) (PEDOT) were used as alignment materials for polymer 1P. The photoluminescence dichroic ratios of 1P on rubbed PI, PA and PEDOT films are 10.4, 8.3 and 7.3, respectively. The electroluminescence dichroic ratio of IP aligned on a PEDOT film is 6.1.
Synthesis and electroluminescence of side-chain liquid crystalline polyacrylates and polyoxiranes containing bistolane side groups
(2002-03-01)
Chang, SW
;
Hsu, CS
;
應用化學系
;
Department of Applied Chemistry
The synthesis and characterization of side-chain liquid crystalline (LC) polyacrylates and polyoxiranes containing bistolane side-groups are presented. The phase behavior of the prepared monomers and polymers was characterized by differential scanning calorimetry and optical polarizing microscopy. All of the obtained monomers and polymers reveal an enantiotropic nematic phase. The birefringences of the LC monomers are in the range from 0.35-0.6 depending on the measuring wavelength. The photoluminescence (PL) and electroluminescence (EL) properties of the obtained monomers and polymers are also reported.
Synthesis of UV-curable liquid crystalline diacrylates for the application of polarized electroluminescence
(2006-01-01)
Yao, YH
;
Kung, LR
;
Chang, SW
;
Hsu, CS
;
應用化學系
Two series of UV-curable rod-like diacrylates containing bis-tolane (M1 - M5) and bis-stilbene (M6 - M10) mesogens were synthesized. All of the diacrylates were prepared through convergent syntheses involving palladium-catalysed coupling reactions. The thermal transitions and mesomorphic properties of the diacrylates were characterized by differential scanning calorimetry and optical microscopy. All the bis-tolane-based monomers reveal nematic phases, except M5 which shows no mesomorphic behaviour. For the bis-stilbene based monomers, most show no mesomorphic behavior and only M7 and M9 exhibit a SmA phase.
Use of WNX as the diffusion barrier for interconnect copper metallization of InGaP-GaAs HBTs
(2004-07-01)
Chang, SW
;
Chang, EY
;
Lee, CS
;
Chen, KS
;
Tseng, CW
Use of WNX as the diffusion barrier for interconnect copper metallization of InGaP-GaAs heterojunction bipolar transistors (HBTs) was studied. The WNX (40 nm) and Cu (400 nm) films were deposited sequentially on the InGaP-GaAs HBT wafers as the diffusion barrier and interconnect metallization layer, respectively, using the sputtering method. As judged from the data of scanning electron microscopy, X-ray diffraction, Auger electron spectroscopy, and sheet resistance, the Cu-WNX-SiN and Cu-WNX-Au structures were very stable up to 550 degreesC and 400 degreesC annealing, respectively. Current accelerated stress test was conducted on the Cu-WNX metallized HBTs with V-CE = 2 V, J(C) = 140 kA/cm(2) and stressed for 55 h, the current gain (beta) of these HBTs showed no degradation and was still higher than 100 after the stress test. The Cu-WNX metallized HBTs were also thermally annealed at 250 degreesC for 25 h and showed no degradation in the device characteristics after the annealing. For comparison, HBTs with An interconnect metallization were also processed, and these two kinds of devices showed similar characteristics after the stress tests. From these results, it is demonstrated that WNX is a good diffusion barrier for the interconnection copper metallization of GaAs HBTs.
Use WNx as diffusion barrier for copper airbridged low noise GaAsPHEMT
(2003-11-27)
Chang, HC
;
Chang, EY
;
Lien, YC
;
Chu, LH
;
Chang, SW
A low noise pseudomorphic high electron mobility transistor (PHEMT) with copper airbridges using sputtered WNx as the diffusion barrier has been developed. Both the material system and the copper airbridged PHEMT with WNx as the diffusion barrier did not decay even after thermal annealing at 250degreesC for 20 h. The results show that the copper airbridges with WNx diffusion barrier can be used as the interconnects for low noise GaAs PHEMTs.