High-speed 1.3 μm GaInAs detectors fabricated on GaAs substrates

High-speed interdigitated metal-semiconductor-metal detectors have been fabricated on non-lattice-matched, semi-insulating, GaAs substrates using two GaInAs layers of differing indium concentrations to accommodate most of the lattice mismatch by interface misfit dislocations. Bandwidths as high as 3 GHz were measured with none of the detrimental low-frequency gain usually observed in this type of device. This is attributed to the inhibition of the surface trapping of photoinduced carriers by a graded pseudomorphic layer at the surface     

GaAs heterostructure FET frequency dividers fabricated with high-yield 0.5 mu m direct-write trilevel-gate-resist

Frequency dividers and FET test structures have been fabricated on selectively doped n/sup +/AlGaAs/GaAs heterostructure FETs (HFETs) with 0.5 mu m gate length electron-beam direct-writing on a novel trilevel resist, EBR-9/Ge/PMGI. A divide-by-two master-slave frequency divider fabricated with direct-coupled FET logic gates operated up to 9.3 GHz. The input frequency range of a divide-by-two transmission-gate frequency divider was from 3.2 to 12.2 GHz, with a supply voltage of 1.2 V at room temperature. The average propagation delay (fan-in and fan-out=1) was 18.2 ps/gate, with a power dissipation of 3.9 mW/stage. With a 3.5 mu m source-drain spacing, a peak transconductance of 360 mS/mm was measured. The functional yield of both discrete devices and circuits was 92% across 2 in-diameter wafers.<>     

A 0.4-μm gate-length AlGaAs/GaAs P-channel HIGFET with 127-mS/mmtransconductance at 77 K

WN-gate, p-channel AlGaAs-GaAs heterostructure insulated-gate field-effect transistors (HIGFETs) fabricated on a metalorganic vapor-phase epitaxy (MOVPE) wafer are discussed. A self-aligned Mg ion implantation (80 keV, 6×10¹³ cm^-2) annealed at 850°C in an arsine atmosphere and the control of the SiO₂ sidewall dimensions allow the fabrication of p-channel HIGFETs with a gate length smaller than 0.5 μm with low subthreshold current. P-channel HIGFETs with 0.4-μm gate lengths exhibit extrinsic transconductances as high as 127 mS/mm at 77 K and 54 mS/mm at 300 K     

A 0.1-μm delta-doped MOSFET fabricated with post-low-energyimplanting selective epitaxy

A simple fabrication technology for delta-doped MOSFETs, named post-low-energy implanting selective epitaxy (PLISE) is presented. The PLISE technology needs no additional photo-lithography mask, deposition step or etching step even for CMOS devices. The only additional step is growing undoped epitaxial channel layers by UHV-CVD after the channel implantation. With this technology, delta-doped NMOSFETs with 0.1-μm gate length were successfully fabricated. By optimizing the epi-layer thickness and the channel doping level, short-channel effects are suppressed enough to achieve 0.1-μm gate length. Moreover, the junction capacitance at zero bias is reduced by 50%     

0.25-μm gate millimeter-wave ion-implanted GaAs MESFETs

Quarter-micrometer gated ion-implanted GaAs MESFETs which demonstrate device performance comparable to AlGaAs/InGaAs pseudomorphic HEMTs (high-electron mobility transistors) have been successfully fabricated on 3-in-diameter GaAs substrates. The MESFETs show a peak extrinsic transconductance of 480 mS/mm with a high channel current of 720 mA/mm. From S-parameter measurements, the MESFETs show a peak current-gain cutoff frequency f_t of 68 GHz with an average f_t of 62 GHz across the wafer. The 0.25-μm gate MESFETs also exhibit a maximum-available-gain cutoff frequency f_t greater than 100 GHz. These results are the first demonstration of potential volume production of high-performance ion-implanted MESFETs for millimeter-wave application     

1.3-μm P-i-N photodetector using GaAs with As precipitates(GaAs:As)

The fabrication of a GaAs detector which operates in the 1.3- to 1.5-μm optical range is reported. The detector is a P-i-N photodiode with an intrinsic layer composed of undoped GaAs which was grown at 225°C and subsequently annealed at 600°C. This growth process has been demonstrated to produce a high density of As precipitates in the low-temperature grown region, which the authors show to exhibit absorption through internal photoemission. The internal Schottky barrier height of the As precipitates is found to be 0.7 eV, leading to reasonable room-temperature responsivity out to around 1.7 μm     

1.55-μm buried-heterostructure VCSELs with InGaAsP/lnP-GaAs/AlAsDBRs on a GaAs substrate

We demonstrate 1.55-μm buried-heterostructure (BH) vertical-cavity surface-emitting lasers (VCSELs) on a GaAs substrate. Thin-film wafer-fusion technology enables InP-based BH VCSELs to be fabricated on GaAs/AlAs distributed Bragg reflectors. Detailed investigations of the device resistance are also described. As a result of introducing BH and obtaining low device resistance, the threshold current density under CW operation shows the independence of mesa size due to a strong index guide and small noneffective current. A 5-μm VCSEL exhibits a record threshold current of 380 μA at 20°C. This VCSEL also operates with single transverse mode up to the maximum optical output power     

A log-polar image sensor fabricated in a standard 1.2-μm ASICCMOS process

A CMOS log-polar or foveated image sensor for use in mobile robotic and machine vision applications has been designed, fabricated, and tested. The sensor benefits from a high degree of integration, minimal power consumption, and ease of manufacture due to the use of a standard 1.2 μm ASIC CMOS process. The sensor is composed of two distinct CMOS imager arrays which together solve the problem of obtaining good image resolution over a wide field of view. With resolution sensing is accomplished with a 40×40 array of individual pixels each measuring 9.6 μm on a side. A wide field of view is provided by an array of 64×16 pixels arranged on a log-polar grid. The maximum measured dynamic range for the fabricated log-polar array is 46 dB, while the lowest observed fixed-pattern noise is 0.5% of saturation. Combined power consumption of both arrays is under 2 mW when operating from a single 5-V supply at a frame rate of 30 frames/s     

1.52-1.59-μm range different-wavelength modulator-integratedDFB-LDs fabricated on a single wafer

We report for the first time different-wavelength modulator-integrated distributed-feedback laser diodes (DFB/MODs) fabricated on a single wafer, whose lasing wavelength cover almost all of the expanded erbium-doped fiber amplifier (EDFA) gain band from 1.527 to 1.593 μm. The devices provided uniform and high-performance characteristics such as a threshold current less than 12 mA and successful transmission of 2.5 Gb/s-600 km through a normal fiber     

A low-power GaAs front-end IC with current-reuse configurationusing 0.15-μm-gate MODFETs

We have developed a novel current-reuse configuration of a front-end integrated circuit (IC), where the current can be reused in the whole circuit blocks that are a low-noise amplifier, local amplifier, and mixer. The power dissipation of the front-end IC is reduced by the factor of three as compared to conventional front-end ICs. Excellent RF performance such as conversion gain of 30 dB and noise figure of 1.6 dB at 1.5 GHz is attained under the conditions of the supply voltage and current of 3.6 V and 3 mA, respectively     

A superlattice GaAs/InGaAs-on-GaAs photodetector for 1.3-μmapplications

A metal-semiconductor-metal detector with a InGaAs/GaAs superlattice active layer showing efficient photoresponse up to 1.35 μm is discussed. The active layer with an In composition of approximately 64% is grown by molecular beam epitaxy on a GaAs substrate at 460°C. The large size detector (200×200 μm²) shows bias-dependent DC gain, fast response speed (FWHM <50 ps), and reasonably low dark current     

Delay time analysis for 0.4- to 5-μm-gate InAlAs-InGaAs HEMTs

InAlAs-InGaAs HEMTs with 0.4- to 5-μm gate lengths have been fabricated and a maximum f_T of 84 GHz has been obtained by a device with a 0.4-μm gate length. A simple analysis of their delay times was performed. It was found that gradual channel approximation with a field-dependent mobility model with E_c of 5 kV/cm holds for long-channel devices (L _g>2 μm), while a saturated velocity model with a saturated velocity of 2.7×10⁷ cm/s holds for short-channel devices (L_g<1 μm)     

High-speed integrated logic with GaAs MESFET's

The feasibility of using GaAs metal-semiconductor field-effect transistors (GaAs MESFET's) in fast switching and high-speed digital integrated circuit applications is demonstrated. GaAs MESFET's with 1-/spl mu/m gate length are shown to have a current-gain-bandwidth product f/SUB T/ equal to 15 GHz. These devices exhibit a 15 ps internal delay in a large-signal switching test. A simple logic circuit consisting of MESFET's and Schottky diodes was monolithically integrated on a semiinsulating GaAs substrate. This logic circuit exhibits a propagation delay of 60 ps with no output load, and 105 ps when its output is loaded by three similar logic gates. A useful bandwidth of approximately 3 GHz is observed.     

High-speed metal-semiconductor-metal photodiodes with Er-doped GaAs

Very high-speed MSM photodiodes have been fabricated on Er-doped GaAs over a doping range of 10¹⁸-10²⁰ cm^-3 . The impulse response (characterized by photoconductive sampling) of these diodes, with finger widths/spacings of 2 μm, has been found to be tunable over a range of about 3 ps-22 ps. Electro-optic sampling was used to characterize MSM diodes with finger widths/spacings of 0.5 μm and 1 μm on a sample with [Er]=10¹⁹ cm^-3, resulting in 3-dB bandwidths of 160 GHz and 140 GHz, respectively, corresponding to pulse widths of 2.7 ps and 3.3 ps. Correlation measurements were also done on the GaAs:Er samples, using an all-electronic Sampling Optical Temporal Analyzer (SOTA) structure     

A 40-Gbit/s superdynamic decision IC fabricated with 0.12-μmGaAs MESFET's

This paper describes a 4O-Gbit/s decision integrated circuit (IC) fabricated with 0.12-μm gate length GaAs metal-semiconductor field-effect transistors (MESFET's). A superdynamic flip-flop circuit and a wide-band amplifier were applied in order to attain 40-Gbit/s operation. A conventional static decision IC was also fabricated for comparison. The dynamic decision IC operated up to 40 Gbit/s, which is twice as fast as the conventional static decision IC. Error-free 40-Gbit/s operation is the fastest among GaAs MESFET decision IC's     

High-speed performance of partly gain-coupled 1.55-μmstrained-layer multiple-quantum-well DFB lasers

A partly-gain-coupled 1.55-μm distributed feedback (DFB) laser with a strained-layer multiple-quantum-well (MQW) active region with high relaxation oscillation frequency and maximum intrinsic bandwidth of 28 GHz is reported. An effective differential gain of 1.80×10^-15 cm² was achieved, which may be attributed to the strain effect in the MQW active region as well as the combination of the longitudinal gain/index coupling mechanism and fast lateral carrier injection from the cladding layers into the wells     

0.4-µm gate-length devices fabricated by contrast-enhanced lithography

This letter describes the fabrication of submicrometer polysilicon-gate MOS devices by an advanced optical process called contrast enhancement. Functional devices having gate lengths as small as 0.4 µm were fabricated with this process. Contrast-enhanced lithography (CEL) allows usable photoresist patterns to be fabricated at smaller dimensions than is possible with conventional resist. The simultaneous replication of mask dimensions for isolated lines at 0.35 µm and above was achieved in this work using a single exposure on an Optimetrix 10:1 DSW system. Contrast enhancement has been applied to the fabrication of n-channel MOS devices having gate lengths from 0.4 to 1.5 µm in steps of 0.1 µm. Long-channel devices were also fabricated. The transconductance of the 0.4-µm devices is 40 mS/mm at Vds= 5 V. Threshold voltages (Vds= 0) are nearly independent of gate length, ranging from 1.21 to 1.31 V over the 7.5- to 0.4-µm range in gate length. The effective mobility for long-channel devices is 430 cm²/V.s.     

A 2.6-GHz/5.2-GHz frequency synthesizer in 0.4-μm CMOStechnology

This paper describes the design of a CMOS frequency synthesizer targeting wireless local-area network applications in the 5-GHz range. Based on an integer-N architecture, the synthesizer produces a 5.2-GHz output as well as the quadrature phases of a 2.6-GHz carrier. Fabricated in a 0.4-μm digital CMOS technology, the circuit provides a channel spacing of 23.5 MHz at 5.2 GHz while exhibiting a phase noise of -115 dBc/Hz at 2.6 GHz and -100 dBc/Hz at 5.2 GHz (both at 10-MHz offset). The reference sidebands are at -53 dBc at 2.6 GHz, and the power dissipation from a 2.6-V supply is 47 mW     

Analysis of a GaAs metal-semiconductor-metal (MSM) photodetectorwith 0.1-μm finger spacing

The temporal response of a GaAs metal-semiconductor-metal (MSM) photodetector with a finger spacing of 0.1 μm is discussed. The intrinsic detector has a minor effect (25% increase) on the full width at half-maximum (FWHM) of the temporal response of the device and its parasitic circuit elements. The analysis indicates that a long time constant due to the decay of holes is solely responsible for this increase. The smallest FWHM for this detector is estimated to be less than 2.5 ps     

High-speed InGaP/GaAs transistors with a sidewall base contactstructure

We have fabricated InGaP/GaAs double heterojunction bipolar transistors with a sidewall base contact structure. These transistors operate in both emitter-up and emitter-down modes. Symmetric characteristics of the cutoff frequency f_T=68 GHz and the maximum oscillation frequency f_max=31 GHz were obtained at a base-collector bias V_BC of 0 V. For emitter-down operation, f _T was found to reach a maximum of 78 GHz when the base-collector junction was forward biased at 0.9 V. The product of f _T for emitter-down operation and f_T for emitter-up operation was 5.3×10³ GHz², which is about six times that of previously reported SiGe heterojunction bipolar transistors