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ABSTRACT: We demonstrate a new S-band nonlinear fibre amplifier, with over 18 dB gain, and S-band wavelength converter, with over 20 nm bandwidth, obtained by combination of Raman gain and optical parametric amplification.
Optical Fiber Communication Conference and Exhibit, 2001. OFC 2001; 04/2001
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ABSTRACT: We have demonstrated a fiber optical parametric amplifier (OPA)
utilizing a highly nonlinear fiber, which allowed us to obtain
substantial gain with only a 20-m length, over a 24-nm bandwidth, even
though the pump was 49 nm from λ<sub>0</sub>. The availability of
such fibers should greatly facilitate the development of fiber OPAs for
applications such as wavelength conversion, phase conjugation, and
broadband amplification
Lasers and Electro-Optics, 1998. CLEO 98. Technical Digest. Summaries of papers presented at the Conference on; 06/1998
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ABSTRACT: Low-base-collector capacitance (C/sub bc/) AlGaAs/GaAs HBTs with f/sub MAX/>200 GHz and f/sub T/=52 GHz have been fabricated. With co-implants of high energy, high dose He/sup +/ and H/sup +/ ions through the external base layer, part of the heavily doped n/sup +/ sub-collector was compensated leading to a decrease in the extrinsic portion of C/sub bc/. The implants caused only a slight increase of base resistance. Using this approach in combination with a standard low dose, shallow collector compensating implant, C/sub bc/ of double implanted HBT's can be reduced by more than 35%.< >
IEEE Electron Device Letters 12/1995; · 2.85 Impact Factor
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ABSTRACT: In this paper we present a novel technique which can significantly
reduce the base-collector capacitance (C<sub>bc</sub>) in AlGaAs/GaAs
HBTs. C<sub>bc</sub>, is a key limiter of HBT microwave gain and
bandwidth. Our process uses high dose, high-energy ion implantation
through the external base layer to compensate part of the heavily doped
sub-collector. It also uses the more conventional self-aligned shallow
implant to compensate the entire collector underneath the base contact.
The total C<sub>bc</sub> of the double implanted HBTs has been reduced
by more than 35% with this new technique as compared to devices with
shallow implant only. Under proper conditions, the double implantation
produces little damage to the base (which can cause an increase in base
resistance R<sub>B</sub>); thus the RF performance can be significantly
improved. An f<sub>MAX</sub> greater than 200 GHz has been obtained,
comparable to the best previous reported results in common emitter HBTs
Device Research Conference, 1995. Digest. 1995 53rd Annual; 07/1995
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ABSTRACT: Electron and hole impact ionization coefficients in (100)Ga 0.5 In 0.5 P have been measured by photomultiplication measurements. The ratio of hole to electron ionization coefficients, β/α, is shown to decrease from 2 to 1 when the electric field is increased from 3.5×10<sup>5</sup> to 6.5×10<sup>5</sup> V/cm. As confirmation, breakdown voltages were measured for several p<sup>+</sup>-n<sup>-</sup>-n<sup>+</sup> diodes with various concentrations in the n<sup>-</sup> region. The values observed showed good agreement with those calculated from the ionization coefficients. Typical breakdown voltages are on the order of 1.6 times higher than those expected for GaAs. © 1995 American Institute of Physics.
Applied Physics Letters 07/1995; · 3.84 Impact Factor
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ABSTRACT: Novel InP-based heterojunction bipolar transistors (HBTs) using an
AlInP pseudomorphic emitter, together with an InP base and collector,
have been fabricated. By using InP as both base and collector, the
advantage of high electron velocity and high breakdown field of InP
collectors are obtained without the problem associated with the energy
barrier between the more standard InGaAs/InP base and collector
heterojunction. Epitaxial layers were grown by gas-source molecular beam
epitaxy (GSMBE). The 200 Å pseudomorphic emitter had an aluminium
fraction of 15%, sufficiently suppressing hole injection from the base.
The DC gain for 40×40 μm<sup>2</sup> devices reached 18. The
breakdown voltage BV<sub>CEO</sub> of 10 V is an improvement over
devices with InGaAs base and collector layers
Electronics Letters 02/1995; · 0.96 Impact Factor
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Device Research Conference, 1994. 52nd Annual; 02/1994
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ABSTRACT: The profiles of AlGaAs/GaAs heterostructures grown by gas‐source molecular beam epitaxy (GSMBE) on patterned substrates at different growth temperatures have been studied. It was found that at higher substrate temperature, the GSMBE growth results in Al clustering and the formation of high index planes. With a proper combination of low growth temperature and etched profile, a quasiplanarized surface is obtainable. A process simulation program is found to be capable of simulating the GSMBE growth profile at lower substrate temperature with reasonable accuracy.
Journal of Applied Physics 09/1993; · 2.17 Impact Factor
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Metalorganic Vapor Phase Epitaxy, 1992. Sixth International Conference; 07/1992
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ABSTRACT: The effective Schottky barrier height on n-type InP is increased by a thin heavily-doped p-type surface layer grown by gas-source molecular beam epitaxy. The relationships between the barrier height increment and the doping level and thickness of the surface layer have been studied. The Schottky diodes fabricated by this method show reasonably low leakage current at high reverse bias and high reverse breakdown voltage.
Electronics Letters 02/1992; · 0.96 Impact Factor
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ABSTRACT: Phosphorus‐controlled growth rate of homoepitaxial (100) InP, GaP, and AlP on GaP substrates by gas source molecular beam epitaxy was investigated. Elemental group‐III sources and thermally cracked phosphine were used. The growth rate was monitored by the specular beam intensity oscillations of reflection high‐energy electron diffraction. This technique gives exact values of V/III ratio on the surface by measuring the amount of phosphorus which is actually incorporated into the film. Here the V/III ratio is defined as P‐controlled growth rate divided by group‐III‐controlled growth rate instead of the beam flux V/III ratio. Also the phosphorus surface desorption activation energies were measured to be 0.61 eV and in the range between 0.89 and 0.97 eV for InP and GaP, respectively.
Applied Physics Letters 02/1991; · 3.84 Impact Factor
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Epitaxial Materials and In-Situ Processing for Optoelectronic Devices, 1991/Microfabrication for Photonics and Optoelectronics, 1991. LEOS 1991 Summer Topical Meetings on;
