D.A. Humphrey

A DC to 20 GHz high gain monolithic InP/InGaAs HBT feedback amplifier

The authors have realized a high-gain, broadband, bipolar feedback amplifier exhibiting an average flatband gain of 30 dB with 6.5-dB/sub p-p/ ripple and a -3-dB bandwidth of 20 GHz. Using InP/InGaAs heterostructure bipolar transistors (HBTs), a gain-bandwidth product of more than 600 GHz was demonstrated for a nondistributed monolithic integrated circuit for the first time. This two-stage transadmittance-transimpedance design has a chip-size of 975 mu m*675 mu m and dissipates 280 mW for a 3-V supply. The input return loss and reverse transmission to 9 GHz were -30 dB and -40 dB, respectively.<<ETX>>

1.0 GHz monolithic p-i-n MODFET photoreceiver using molecular beam epitaxial regrowth

A single-stage integrating front-end photoreceiver comprising a p-i-n In/sub 0.53/Ga/sub 0.47/As photodiode integrated with a selectively regrown pseudomorphic In/sub 0.65/Ga/sub 0.35/As/In/sub 0.52/Al/sub 0.48/As MODFET using MBE regrowth was investigated. Cutoff frequencies of the 1.0- mu m regrown MODFETs were f/sub t/=24 GHz and f/sub max/=50 GHz. Transconductances of the regrown MODFETs were as high as 495 mS/mm with a current density (I/sub ds/) of 250 mA/mm. The 3-dB bandwidth of the photoreceiver was measured to be 1 GHz. The bit rate sensitivity at 1 Gb/s was -29.6 dBm for BER 10/sup -9/ using 1.55- mu m excitation. The single-stage amplifier exhibited up to 25 dB of flatband gain of the photocurrent.<<ETX>>

Reduction of 1/f noise current with non-equilibrium electron transport in AlInAs/InGaAs heterojunction bipolar transistors

We report on the reduction of 1/f noise current by utilizing the non-equilibrium carrier transport in AlInAs/InGaAs HBTs. A 10-dB reduction in the equilibrium input noise current density is obtained by reducing the base thickness from 100 nm to 70 mn for transistors with emitter dimensions of 3/spl times/5 /spl mu/m/sup 2/. As the result, a 1/f noise corner frequency of 1.55 kHz is obtained. This is the lowest 1/f corner frequency amongst any compound semiconductor devices reported to date.<<ETX>>

8-element linear array monolithic p-i-n MODFET photoreceivers using molecular beam epitaxial regrowth

An 8-element linear array of single-stage integrating front-end photoreceivers using molecular beam epitaxial (MBE) regrowth was investigated. Each element consisted of a p-i-n In/sub 0.53/Ga/sub 0.47/As photodiode integrated with a selectively regrown pseudomorphic In/sub 0.65/Ga/sub 0.35/As/In/sub 0.52/Al/sub 0.48/As MODFET. Cutoff frequencies of 1.0- mu m discrete regrown MODFETs were f/sub t/=24 GHz and f/sub max/=50 GHz. Transconductance of the regrown MODFETs was as high as 495 mS/mm with a current density (I/sub ds/) of 250 mA/mm. The 3-dB bandwidth of the photoreceiver was measured to be 1 GHz. The bit rate sensitivity at 1 Gb/s was -31.8 dBm for BER 10/sup -9/ using 1.55 mu m excitation for a photoreceiver with an anti-reflection coating. The single-stage amplifier exhibited up to 25 dB flatband gain of the photocurrent, and a two-stage amplifier was up to 31 dB of gain. Good uniformity between each photoreceiver element in the array was achieved. Electrical crosstalk between photoreceiver elements was estimated to be approximately -34 dB.<<ETX>>

An edge-coupled receiver OEIC using AlInAs/InGaAs HBTs

The authors report on a novel edge-coupled optical receiver optoelectronic integrated circuit (OEIC) fabricated in AlInAs/InGaAs heterostructure bipolar transistor (HBT) technology. The edge coupled geometry is compatible with the multi-fiber array connector technology. The receiver consists of a waveguide pin detector, a transimpedance preamplifier and a second voltage amplifier stage. The pin has been realized in a standard HBT layer structure and requires no additional growth or processing steps.<<ETX>>

Carbon-doped InGaP/GaAs/InGaP double heterojunction bipolar transistors with a very low 1/f noise corner frequency of 108 kHz grown by chemical beam epitaxy

We report on the low frequency noise characteristics of InGaA/GaAs/InGaP double heterojunction bipolar transistors with a carbon-doped base grown by chemical beam epitaxy. Transistors with 2.5 nm base setback layer show a very high common emitter current gain of 120 and a very low collector saturation voltage of 75 mV at room temperature. Very low 1/f current noise corner frequency of 108 kHz is obtained because of the use of high quality direct-gap InGaP material as the wide-gap emitter

Non-equilibrium transport in ultra-fast InGaAs/InP heterostructure bipolar transistors

The physics of non-equilibrium electron transport in ultra-fast InGaAs/InP heterojunction bipolar transistors (HBTs) is discussed. The forward transit delay was measured as a function of temperature from 340 K to 150 K. The small value of tau /sub F/=0.28 ps at a lattice temperature of 150 K is due to the dominance of high velocity ( upsilon approximately 6*10/sup -7/ cm-s/sup -1/) Gamma -valley electron transport in the base and collector. It is shown that optic-phonon and electron-electron scattering must be considered to properly describe the temperature dependence of electron transport in the collector.<<ETX>>

Strain and vertical scaling in the base of Al/sub 0.48/In/sub 0.52/As/In/sub x/Ga/sub 1-x/As heterostructure bipolar transistors

The authors present two experimental results which are of direct consequence in the design of high-performance n-p-n AlInAs/InGaAs heterostructure bipolar transistors (HBTs). First, it is shown that the effective heterostructure valence band offset is independent of composition and strain for pseudomorphic base In/sub x/Ga/sub 1-x/As HBTs in the range 0.5<x<0.6. Second, the effect of vertical scaling on the static and dynamic transistor behavior is demonstrated. For base thickness, X/sub B/<1000 AA, the injected electrons maintain a nonequilibrium distribution throughout the base resulting in unconventional 1/X/sub B/ scaling of the common emitter current gain, enhancement of avalanche multiplication in the collector, and negligible base delay time.<<ETX>>

Integrated photoreceiver array using molecular beam epitaxial regrowth

A photoreceiver linear array of 8-elements each composed of a p-i-n In/sub 0.53/Ga/sub 0.47/As photodiode integrated with a selectively regrown pseudomorphic In/sub 0.65/Ga/sub 0.35/As/In/sub 0.52/Al/sub 0.48/As modulation doped field effect transistor (MODFET) using molecular beam epitaxial (MBE) regrowth is investigated. MBE selective area regrowth enables a planarized monolithic integration with reduced parasitic capacitance over vertical monolithic integration. Cutoff frequencies (f/sub T/ and f/sub max/) of 58 GHz and 67 GHz and 24 GHz and 51 GHz were determined for as-grown and regrown MODFETs, respectively. A 3-dB bandwidth of 1 GHz was measured for the circuit. The bandwidth of the circuit is limited by the photodiode response.<<ETX>>