In DESIRE process, silylation is probably the most critical step since the final resist profiles are mainly determined by the Si distribution between the exposed and unexposed areas of the upper part of the resist. In...
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A theoretical model for quantum well varactors is presented. The model is used to calculate the device C-V and I-V characteristics and very good agreement has been found between the calculated and measured results. Ba...
A theoretical model for quantum well varactors is presented. The model is used to calculate the device C-V and I-V characteristics and very good agreement has been found between the calculated and measured results. Based on the model, a triple barrier double well varactor has been designed and fabricated. A very high capacitance ratio within a very small bias range is achieved, as designed. Details of the design calculations and experimental results are presented.
The properties of lattice-matched (x = 0.53) and strained (x = 0.65) In0.52Al0.48As/InxGa1-xAs p-doped channel FET's are reported. The role of doping density is studied with the help of two designs (dual-channel w...
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The properties of lattice-matched (x = 0.53) and strained (x = 0.65) In0.52Al0.48As/InxGa1-xAs p-doped channel FET's are reported. The role of doping density is studied with the help of two designs (dual-channel with low doping and single-channel with high doping). The strained dual-channel devices demonstrate an improvement of mobility from 108 cm2/V . s (53% In) to 265 cm2/V . s (65% In) at 300 K. The corresponding intrinsic transconductance enhancement is from 23 mS/mm (53% In) to 46.5 mS/mm (65% In) using 1.0-mu-m-long gates. The cutoff frequenty (f(T)) also improves from 1.0 to 1.4 GHz. The impact of strain in the highly doped single-channel device is small. The band structure under lattice-matched and strained conditions and the position of the Fermi level according to doping seem to be the main factors determining the reported features.
The third order intermodulation distortion (IMD3) mechanisms of HBT's are analyzed using Volterra Series theory. A T-equivalent circuit is used for the large-signal model of the HBT. The third order nonlinear curr...
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The third order intermodulation distortion (IMD3) mechanisms of HBT's are analyzed using Volterra Series theory. A T-equivalent circuit is used for the large-signal model of the HBT. The third order nonlinear currents generated by the device nonlinearities are evaluated for this purpose and current cancellation is discussed. It is found that, even though the C(je) and g(je) related currents do not show pronounced cancellation, the total base-emitter current and the total base-collector current cancel partially. Second harmonic loading is addressed in view of IMD3 optimization while, at the same time, maintaining high gain through conjugate matching at the fundamental frequency. IMD3 is very sensitive to the nonlinear currents generated by g(je) and alpha. Optimum IMD3 occurs at high second harmonic reflection coefficients corresponding to open load conditions. Finally, minimum and maximum IMD3 occurs for second harmonic load reflection coefficient phases close to analogous extremes of the dominant nonlinear current of the device.
A general approach based on a physical model of impact ionization to fit and extrapolate measured ionization coefficients of electrons-alpha and holes-beta in III-V semiconductors is described. Materials being conside...
A general approach based on a physical model of impact ionization to fit and extrapolate measured ionization coefficients of electrons-alpha and holes-beta in III-V semiconductors is described. Materials being considered include GaAs, AlxGa1-xAs (x=0.1-0.4), InP, In0.53Ga0.47As, and In0.52Al0.48As. Expressions giving the correct dependencies are obtained at very large or small electric fields outside the range of most measurements while at the same time a reasonable fit is achieved for experimental data. The results of the proposed approach yielded a set of physical parameters, which can be coupled with the temperature-dependence relationships in the model to predict impact ionization coefficients over a wide range of electric fields at different temperatures, and can be useful in calculations of temperature-dependent avalanche breakdown voltages of electronic and optical devices.
The high-speed and noise performance of 0.15-μm gate GaAs MESFETs for microwave and millimeter-wave IC applications is reported. The best extrinsic ft is 109 GHz without correction for pad parasitics, which is equiva...
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The high-speed and noise performance of 0.15-μm gate GaAs MESFETs for microwave and millimeter-wave IC applications is reported. The best extrinsic ft is 109 GHz without correction for pad parasitics, which is equivalent to an intrinsic ft of 134 GHz. The 0.15-μm × 200-μ gate GaAs MESFET achieved a 0.6-dB noise figure with a 17-dB associated gain at 10 GHz and a 0.9-dB noise figure with a 13-dB associated gain at 18 GHz. THe measured noise figure and associated gain are the best reported for GaAs MESFETs and are comparable to the best noise/gain performance of HEMTs and P-HEMTs.
The experimental characteristics of a monolithic D-band oscillator-doubler chain are reported together with the design, monolithic integrated circuit (MMIC) implementation, and testing. The circuits were fabricated us...
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The design, fabrication and experimental characteristics of a balanced InAlAs/InGaAs heterostruc-ture diode mixer are presented. The mixer is mono-lithically integrated on InP substrates and shows a minimum conversion...
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A thermally stable Pd/Ge/Ti/Pt/ ohmic contact with low specific contact resistance was formed on both n and p+-GaAs. The lowest specific contact resistances were 4.7×10-7 and 6.4×10-7 Ω.cm2 for the n and p+...
A thermally stable Pd/Ge/Ti/Pt/ ohmic contact with low specific contact resistance was formed on both n and p+-GaAs. The lowest specific contact resistances were 4.7×10-7 and 6.4×10-7 Ω.cm2 for the n and p+-GaAs, respectively, when the n-GaAs was doped with Si to 2×1018cm-3, and the p+-GaAs was doped with carbon to 5×1019 cm-3. Interfacial reactions and element diffusions of the contacts were investigated by using transmission electron microscopy, Auger electron spectrometry with depth profiles. All the contacts were thermally stable at 300 °C for 20 hours, and it appeared that the p-contacts were more stable than the n-contacts.
The experimental characteristics of a monolithic D-band oscillator-doubler chain are reported, together with the design, monolithic integrated circuit (MMIC) implementation, and testing. The circuits were fabricated u...
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The experimental characteristics of a monolithic D-band oscillator-doubler chain are reported, together with the design, monolithic integrated circuit (MMIC) implementation, and testing. The circuits were fabricated using submicron (0.1- mu m) InAlAs/InGaAs high-electron-mobility transistors (HEMTs) and had on-chip bias stabilization circuitry and an integrated E-field probe for direct radiation into the waveguide. The oscillation signal was detected over a frequency range of 130.5 GHz to 132.8 GHz with an output power of -12 dBm for designs with small-gate-periphery (45- mu m) HEMTs.< >
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