The development of heterojunction integrated injection logic

The development of heterojunction integrated injection logic (HI ²L) since 1982 is described. The baseline process that uses AlGaAs/GaAs emitter-down HBTs (heterojunction bipolar transistors) as the switching element is presented. Two sets of design rules, one using a 7.0-μm collector and 8.0-μm metal pitch and another using a 5.0-μm collector and 5.0-μm metal pitch, have been developed for the pilot line circuit fabrication. Typical propagation delays obtained for a fan-out=4 HI²L gate using the 7.0- and 5.0-μm collector processes are 250 and 150 ps, respectively, at a power dissipation of 5 mW per gate. LSI and VLSI circuits as complex as 4 K-gate arrays and 32-bit MIPS microprocessors have been fabricated successfully using the HI²L technology     

High-gain W band pseudomorphic InGaAs power HEMTs

The authors have fabricated 0.1-μm T-gate pseudomorphic (PM) InGaAs power high-electron-mobility transistors (HEMTs) with record power and gain performance at 94 GHz. Devices with 40-μm gate peripheries achieved 10.6-mW output power with 7.3-dB gain and 14.3% power-added efficiency (PAE). Devices with 160-μm gate peripheries achieved 62.7-mW output power with 4.0-dB gain and 13.2% PAE. The authors believe the superior performance of these devices is due to the combination of a short 0.1-μm T-gate, high-quality material, optimized device profile, and the reduction in source inductance due to source vias     

⟨110⟩-oriented GaAs MESFETs

GaAs metal semiconductor field-effect transistors (MESFETs) have been successfully fabricated on molecular-beam epitaxial (MBE) films grown on the off-axis (110) GaAs substrate. The (110) substrates were tilted 6° toward the (111) Ga face in order to produce device quality two-dimensional MBE growth. Following the growth of a 0.4-μm undoped GaAs buffer, a 0.18-μm GaAs channel with a doping density of 3.4×10¹⁷ cm^-3 and a 0.12-μm contact layer with a doping density of 2×10¹⁸ cm^-3, both doped with Si, were grown. MESFET devices fabricated on this material show very low-gate leakage current, low output conductance, and an extrinsic transconductance of 200 mS/mm. A unity-current-gain cutoff frequency of 23 GHz and a maximum frequency of oscillation of 56 GHz have been achieved. These (110) GaAs MESFETs have demonstrated their potential for high-speed digital circuits as well as microwave power FET applications     

Stable operation (over 5000 h) of high-power 0.98-μm InGaAs-GaAsstrained quantum well ridge waveguide lasers for pumpingEr3+-doped fiber amplifiers

A maximum output power of 115 mW and a slope efficiency of 0.92 W/A have been achieved in 0.98-μm InGaAs strained quantum well lasers with a 3-μm-wide ridge waveguide structure for efficient fiber coupling. Stable operation of over 5000 h under 50°C constant power operation with an optical power density of 3.9 MW/cm² has been demonstrated with a degradation rate as low as 5×10^-6 per hour. These results show that this device is promising as a practical pumping source for Er³⁺-doped fiber optical amplifiers     

Semiconductor pump laser technology

Recent progress in high-power semiconductor lasers for erbium-doped fiber amplifiers is described, focusing on 1.48-μm InGaAsP/InP lasers and 0.98-μm InGaAs/GaAs lasers. The experimental output powers exceed 200 mW (the maximum power was 325 mW) for 1.48-μm lasers, and simulation results indicate that over 400 mW could be obtained by optimizing parameters in strained-layer (SL) multiple-quantum-well (MQW) lasers. Stable operation over a few thousand hours under 100-mW power is demonstrated for liquid-phase-epitaxy-grown lasers, MQW lasers, and SL-MQW lasers grown by all-metal organic vapor-phase epitaxy (MOVPE). For 0.98-μm lasers, improvement in the fiber coupling efficiencies and long-term reliabilities are described. Their power coupled into a single-mode fiber has reached over 100 mW, with coupling efficiencies of approximately 40%. Although reliability seems to be one of the drawbacks compared with 1.48-μm lasers, stable operation for over 10,000 h at 50°C and 30 mW has been reported     

Bottom-emitting VCSEL's for high-CW optical output power

Bottom-emitting vertical-cavity surface-emitting InGaAs MQW lasers operating in the 980-nm wavelength regime have been designed for high continuous-wave optical output power. Devices of 200-μm active diameter and optimized performance reach 350-mW maximum output power when mounted on a heat sink. 50-μm-size lasers produce 100 mW at 25% electrical to optical power conversion efficiency. Thermal properties and size dependent basic characteristics are investigated in detail     

Low-loss 1.3-μm MQW electroabsorption modulators forhigh-linearity analog optical links

Low-loss InAsP-GaInP multiquantum-well electroabsorption waveguide modulators have been developed for transmitting microwaves as subcarriers over optical fibers. The fiber-to-fiber insertion loss is only 5 dB at 1.32-μm wavelength. The electrooptic slope efficiency of an 185-μm-long 11-GHz bandwidth device is equivalent to a Mach-Zehnder modulator with a V_π of 2.2 V. The linearity performance was characterized for a test link without any form of amplification. A RF-to-RF link efficiency of -25.5 dB, noise figure of 27 dB and suboctave spurious-free dynamic range of 114 dB.Hz^4/5 have been achieved with 16 mW input optical carrier power. The measured 3-dB electrical bandwidth exceeds 20 GHz for a 90-μm-long device     

Cavity length dependence of optical characteristics in high powernarrow stripe GaAs superluminescent diodes

A high-power planar structure GaAs superluminescent diode (SLD) with a 5-μm-wide partially current injected region with a 30-200-μm cavity length has been developed by using a simple wafer process of spin-on-glass Zn selective diffusion. Drastic changes in optical characteristics from the light emitting diode mode to the SLD mode have been observed with increasing cavity length, reflecting the gain of the SLD mode. Experimental results of the far-field patterns, the maximum power output, and the optical spectrum show that the best suited cavity length should be designed carefully depending on the object of practical use     

High-temperature performance of InGaAs-InGaAlAs-InP 1.79-μmdiode lasers grown in solid-source molecular-beam epitaxy

1.79-μm InGaAs-InGaAlAs strained-layer quantum-well diode lasers have been fabricated. A characteristic temperature of 72 K has been achieved. At a temperature as high as 100°C, a continuous-wave output power of more than 6.5 mW per facet has been demonstrated with lasers using as-cleaved facets as mirrors     

A 5-μm-wide 18-cm-long low-loss YBa2Cu3O7-δ coplanar line for future multichip moduletechnology

Narrow and low-loss YBa₂Cu₃O_7-δ (YBCO) coplanar lines, which can be used in multichip module technology for future high-density and high-speed digital circuits, have been developed. Etch-back planarization and a patterning process combining Ar-ion milling and wet-etching enabled us to form an 18-cm-long 5-μm-wide YBCO coplanar line without electrical shorts, even for the narrow spacing of 2.5 μm. The surface resistance of this line was kept at a level comparable to that of 10- or 25-μm-wide YBCO coplanar lines and also comparable to that of unpatterned films. This indicates successful fabrication of the 5-μm-wide YBCO coplanar line without notable loss increase resulting from process damage. The 5-μm-wide line showed a low-transmission loss of 0.49 dB at 10 GHz and 55 K. This level of loss is similar to that in Cu coaxial cables. No significant increase in transmission loss was observed up to an input power level of 16 mW at 10 GHz and 55 K. This input power is comparable to the power-handling capability required for transmitting high-speed digital signals through the lines with characteristic impedance of 50 Ω. These results show that the narrow 5-μm-wide YBCO coplanar line has great potential for high-density and high-speed digital circuits     

A 46-ns 1-Mbit CMOS SRAM

A 1-Mb (128 K×8-bit) CMOS static RAM (SRAM) with high-resistivity load cell has been developed with 0.8-μm CMOS process technology. Standby power is 25 μW, active power 80 mW at 1-MHz WRITE operation, and access time 46 ns. The SRAM uses a PMOS bit-line DC load to reduce power dissipation in the WRITE cycle, and has a four-block access mode to reduce the testing time. A small 4.8×8.5-μm² cell has been realized by triple-polysilicon layers. The grounded second polysilicon layer increases cell capacitance and suppresses α-particle-induced soft errors. The chip size is 7.6×12.4 mm²     

GaAs DCFL 2.5 Gbps 16-bit Multiplexer/Demultiplexer LSI's

GaAs 2.5 Gbps 16 bit MUX/DEMUX LSI's have been successfully developed. DCFL is employed as a basic gate in order to reduce the power dissipation. To avoid the speed degradation caused by using DCFL, various technologies such as 8×2(MUX)/2×8(DEMUX) data conversion processes, a Selector Merged Shift Register, clock overlapping, and a 0.7-μm BPLDD MESFET, have been introduced. Moreover the ECL I/O level interface and single power supply features make it easy to use MUX/DEMUX in optical communication systems. The maximum operating data rate is 3.2 Gbps for both LSI's, and the power dissipation of chips which operates with 2.5 Gbps are as low as 1.3 W for each MUX/DEMUX     

Light-emitting diode emitting at 650 nm with 200-MHz small-signalmodulation bandwidth

State-of-the-art modulation bandwidths are presented for multiquantum well resonant cavity light emitting diodes (RCLED's) emitting at 650 nm. 84-μm size epoxy coated RCLED's have a 1.4-mW (CW) output power and a small signal modulation bandwidth of 200 MHz at 40 mA bias. 150-μm diameter devices yield 3.25-mW and 150-MHz bandwidth at 70-mA bias. An open eye-diagram at 622 Mb/s achieved for the 84-μm device makes it very attractive for SONET OC-12 data communication links     

Transconductance amplifier structures with very smalltransconductances: a comparative design approach

A family of CMOS operational transconductance amplifiers (OTAs) has been designed for very small G_m's (of the order of nanoamperes per volt) with transistors operating in moderate inversion. Several OTA design schemes such as conventional, using current division, floating-gate, and bulk-driven techniques are discussed. A detailed comparison has also been made among these schemes in terms of performance characteristics such as power consumption, active silicon area, and signal-to-noise ratio. The transconductance amplifiers have been fabricated in a 1.2-μm n-well CMOS process and operate at a power supply of 2.7 V. Chip test results are in good agreement with theoretical results     

A 150-V multiple up-drain VDMOS, CMOS, and bipolar process in`direct-bonded' silicon on insulator on silicon

Silicon on insulator on silicon (SOIS) has been produced with silicon direct bonding (SDB). Within a silicon film of 15-μm thickness, islands with ubiquitous oxide isolation have been formed for the simultaneous integration of 150-V power VDMOS transistors, CMOS circuits in a channelless sea-of-gates array with 2-μm gates, and bipolar transistors. The up-drain VDMOS transistors with 2-Ω-mm ² specific on-resistance allow multiple isolated outputs, so high-voltage push-pull drivers can be fabricated in a single chip. The bipolar transistors are comparable to those of a 60-V standard process with vertical n-p-n and lateral p-n-p current gains of 80     

High-power high-efficiency quasi-CW Sb-based mid-IR lasers using1.9-μm laser diode pumping

Power efficiency is a critical issue for mid-infrared (mid-IR) semiconductor lasers. Previously, the highest power and efficiency 4-μm laser was pumped with 0.98-μm laser diode. This letter used 1.9-μm diode pumping for better quantum defect ratio and heat flow geometry. A 3.7-μm InAsSb-AlAsSb laser yielded a pump-power-limited 1.25-W single-ended output in 1-ms-long pulse with 6.5% net optical-to-optical efficiency, in contrast with a 0.67-W thermally limited output and 2.7% efficiency with 0.98-μm diode pumping, at 70 K. The results are believed to represent the highest quasi-continuous-wave power from a single device, highest efficiency, and, scaled to the emitting aperture, highest power density for any 3-4-μm semiconductor laser for 1-ms pulse and ⩾70 K     

Efficient Nd:YAG slab longitudinally pumped by diode lasers

An efficient scalable 1.06-μm continuous-wave (CW) Nd:YAG slab laser longitudinally pumped by diode lasers is discussed. The 809-nm diode radiation is focused into every laser channel emerging from the reflection points of the 1.06-μm beam on the coated slab surfaces. A maximum CW TEM₀₀ output power of 675 mW has been obtained at a diode pump power of 2 W resulting in a slope efficiency of 40%     

1-V power supply high-speed digital circuit technology withmultithreshold-voltage CMOS

1-V power supply high-speed low-power digital circuit technology with 0.5-μm multithreshold-voltage CMOS (MTCMOS) is proposed. This technology features both low-threshold voltage and high-threshold voltage MOSFET's in a single LSI. The low-threshold voltage MOSFET's enhance speed performance at a low supply voltage of 1 V or less, while the high-threshold voltage MOSFET's suppress the stand-by leakage current during the sleep period. This technology has brought about logic gate characteristics of a 1.7-ns propagation delay time and 0.3-μW/MHz/gate power dissipation with a standard load. In addition, an MTCMOS standard cell library has been developed so that conventional CAD tools can be used to lay out low-voltage LSI's. To demonstrate MTCMOS's effectiveness, a PLL LSI based on standard cells was designed as a carrying vehicle. 18-MHz operation at 1 V was achieved using a 0.5-μm CMOS process     

Submicrometer n+-Ge gate AlGaAs/GaAs MISFETs

Submicrometer n⁺-Ge gate AlGaAs/GaAs MISFETs have been developed by designing a fabrication process for the n⁺-implanted region. The short-channel effect was sufficiently suppressed by lowering the ion-implantation energy down to 50 keV to achieve a standard deviation of threshold voltage as small as 13 mV for 0.5-μm-gate FETs in a 2-in-diameter wafer. The source resistance was reduced by increasing the annealing temperature to 850°C to obtain a transconductance of 500 mS/mm for a 0.5-μm-gate FET. Even after annealing at such a high temperature, the quality of the channel layer was maintained at a sufficient level to realize a large cutoff frequency of 70 GHz for a 0.4-μm-gate FET. A divide-by-four static frequency divider was also fabricated using the above-mentioned fabrication technology. Successful operation at 16 GHz at 300 K was obtained with a divider using 0.9-μm-gate FETs at a low power dissipation of 36 mW per T-flip-flop     

A high performance 0.35-μm 3.3-V BiCMOS technology optimized forproduct porting from a 0.6-μm 3.3-V BiCMOS technology

A 0.35-μm logic technology has been developed with high performance transistors and four layers of planarized metal interconnect. A 2.5-V version offers lower power and higher performance. A 3.3-V BiCMOS version has been optimized for compatibility with previous designs implemented in a 0.6-μm 3.3-V BiCMOS process. A two-step design process for converting an existing production worthy 0.6-μm 3.3-V BiCMOS design to a 0.35-μm design is described. The silicon results are described