Browsing by Author "Biswas, D"

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Composite-channel metamorphic high electron mobility transistor for low-noise and high-linearity applications
(2004-07-01)
Chang, EY
;
Lin, YC
;
Chen, GJ
;
Lee, HM
;
Huang, GW
A metamorphic high-electron-mobility transistor (MHEMT) with In0.55Ga0.45As/In0.67Ga0.33As/In0.55Ga0.45As composite channel layers was developed for low-noise and high-linearity applications. The use of: a composite channel results in high electron mobility and good confinement of electrons in the channel region which are the desired characteristics of low-noise and high-linearity devices. The noise figure of the 0.25 x 160 mum(2) devices is 0.23 dB with 15.06 dB associated gain, and the output third-order intercept point (IP3) is 18.67 dBm at 6 GHz. The device shows great potential for high-linearity and low-noise applications at high frequencies.
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.
InGaP/InGaAs PHEMT with high IP3 for low noise applications
(2004-06-10)
Lin, YC
;
Chang, EY
;
Chen, GJ
;
Lee, HM
;
Huang, GW
A low noise InGaP/InGaAs pseudomorphic high-electron-mobility transistor (PHEMT) with high IN was developed. The device utilises InGaP as the Schottky layer to achieve a low noise figure and uses AlGaAs as the spacer to reform the electron mobility and contains dual delta doped layers to improve the device linearity.
Weak localization and electron-electron interaction in disordered V80Al20-xFex alloys at low temperature
(2004-08-02)
Biswas, D
;
Meikap, AK
;
Chattopadhyay, SK
;
Chatterjee, SK
;
Lin, JJ
In this Letter we report on the electrical resistivity and magneto-resistivity of disordered V80Al20-xFex alloys in the temperature range 1.5 less than or equal to T less than or equal to 300 K and analyze them in the light of weak localization and electron-electron interaction. The low temperature zero field resistivity obeys a T-1/2 law, which is explained by electron-electron interaction. The low field magneto-resistivity is described by weak localization theory under strong spin-orbit interaction. The electron-phonon scattering rate obeys a quadratic temperature dependence. This observation is interpreted by the existing theories of electron-phonon interaction. (C) 2004 Elsevier B.V. All rights reserved.