M.W. Pierce

Self-aligned AlInAs-GaInAs heterojunction bipolar transistors and circuits

AlInAs-GaInAs heterojunction bipolar transistors (HBTs) and static flip-flop frequency dividers have been fabricated. An f/sub t/ and an f/sub max/ of 49 and 62 GHz, respectively, have been achieved in a device with a 2*5- mu m/sup 2/ emitter. Current-mode logic (CML) was used to implement static divide-by-two and divide-by-four circuits. The divide-by-two circuit operated at 15 GHz with 82-mW power dissipation for the single flip-flop. The divide-by-four circuit operated at 14.5 GHz with a total chip power dissipation of 444 mW.<<ETX>>

33-GHz monolithic cascode AlInAs/GaInAs heterojunction bipolar transistor feedback amplifier

Microwave cascode feedback amplifiers with 8.6-dB gain and DC to 33-GHz bandwidth were developed. The amplifiers utilize AlIn-As/GaInAs heterojunction bipolar transistors having f/sub max/=70 GHz and f/sub tau /=90 GHz. Because of the significant collector-base feedback time constant the cascode configuration provides a large improvement in amplifier bandwidth, but a low-impedance bias node must be provided for the common-base transistor. An active bias network was thus used which eliminates the need for on-wafer Si/sub 3/N/sub 4/ bypass capacitors. >

Monolithic fabrication of NPN and PNP AlInAs/GaInAs HBTs

The authors demonstrated the feasibility of a new technique for the monolithic fabrication of complementary heterostructure bipolar transistors (HBTs). The process led to coplanar npn and pnp HBTs, the first in the AlInAs/GaInAs material system, which were comparable with the state of the art in HBTs. These devices exhibited unity current gain cutoff frequencies (f/sub T/) up to 99 GHz and 14 GHz for the npn and pnp transistors, respectively. The fabrication scheme allows each of these device types to have individually designed epitaxial structures that are grown in a single molecular beam epitaxy run. Results show that the devices will be capable of tight packing densities for IC applications.<<ETX>>

AlInAs/GaInAs HBT IC technology

CML ring-oscillators and static frequency divider circuits implemented with AlInAs/GaInAs heterojunction bipolar transistors (HBTs) lattice matched to InP substrates are demonstrated. A cutoff frequency (f/sub t/) and a maximum frequency of oscillation of 90 GHz and 70 GHz, respectively, have been achieved with a 2*5- mu m/sup 2/ emitter. The ring oscillators demonstrated a 15.8 ps gate delay. The divide-by-two and divide-by-four circuits operated at 22 GHz and 24.8 GHz, respectively.<<ETX>>

High speed dual modulus dividers using AlInAs-GaInAs HBT IC technology

4/5 and 8/9 dual-modulus prescalers are fabricated using AlInAs-GaInAs heterojunction bipolar transistors (HBTs) which operate at clock frequencies up to 9 GHz and which dissipate 700 mW and 900 mW, respectively. The transistor technology results in a cutoff frequency and maximum frequency of oscillation of 90 GHz and 70 GHz, respectively. The 4/5 and 8/9 dividers consists of 106 and 124 transistors, respectively. These are the largest circuits fabricated with HBTs on InP substrates and are among the fastest reported dual-modulus prescalers. The AlInAs-GaInAs HBT technology, circuit design, and measurement results are described.<<ETX>>

36-GHz static digital frequency dividers in AlInAs-GaInAs HBT technology

Summary form only given. Static divide-by-four circuits have been fabricated that operate up to 36 GHz using AlInAs-GaInAs heterojunction bipolar transistor (HBT) IC technology processing an f/sub t/ and f/sub max/ of 110 and 73 GHz, respectively. The transistors used consisted of an abrupt emitter-base junction design which incorporated a low-temperature p-GaInAs spacer as part of the base to inhibit beryllium diffusion. The AlInAs-GaInAs HBT device layers were grown lattice-matched to semi-insulating InP substrates by solid-source molecular beam epitaxy (MBE). >

48 GHz AlInAs/GaInAs heterojunction bipolar transistors

The authors report on the DC and RF performance of self-aligned Al/sub 0.48/In/sub 0.52/As-Ga/sub 0.47/In/sub 0.53/As heterojunction bipolar transistors (HBTs). The properties that make the AlInAs/GaInAs material system extremely attractive for HBTs are discussed The epitaxial layer structure was grown by molecular beam epitaxy on semi-insulating InP. The device structure is shown in cross section. A large variety of HBT devices with different emitter sizes and with different numbers of emitter fingers have been fabricated. The common emitter characteristics of a single 5- mu m*5 mu m emitter are reported.<<ETX>>

Emitter injection and collector current ideality in abrupt heterojunction AlInAs/GaInAs HBTs

Abstract We investigated the electron injection process for high-speed N-p-n AlInAs/GaInAs HBTs by measuring collector and base currents as a function of base-emitter voltage with collector-base voltage equal to zero (Gummel plots) at temperatures from 77 to 300 K. We compared the measured collector current with calculations based on electron injection from emitter to base by tunneling through the conduction band spike and thermionic emission over it, using a modified version of the thermionic-field emission theory developed by Crowell and Rideout. Good agreement was obtained between the experimental collector current ideality factor and tunneling-thermionic emission theory for all temperatures and currents. This is an improvement over drift-diffusion and thermionic emission models, which have been used for HBTs but which do not correctly describe the experimentally observed temperature and current dependence of the ideality of the collector current. The tunneling-thermionic emission model explains the increase in collector current ideality factor that occurs as the transistor is biased at high collector current density ( J C ≧ 10 5 A cm −2 ), which is the regime of operation in which fT is maximized and a low ideality factor is most important. The model also explains the experimentally observed variation of hFE with ln IC. Thus the tunneling-thermionic emission model is a useful aid in the design of the epitaxial structure for high-frequency HBTs.

6-GHz AlInAs/GaInAs/InP DHBT's grown by MOVPE+MBE

Summary form only given. N-p-n AlInAs/GaInAs/InP double-heterojunction bipolar transistors (DHBTs) have been fabricated. They operated with common emitter current gains to over 125 and cutoff frequencies (both f/sub T/ and f/sub max/) of approximately 60 GHz. The epitaxial structures for these devices were grown in a two-step sequence utilizing MOVPE for the InP collector structure followed by solid source MBE for the growth of the GaInAs base and AlInAs emitter structures. The DHBTs were fabricated as emitter-up, mesa transistors with self-aligned base contacts. The MOVPE-grown portion consisted of a 690-nm GaInAs (n/sup +/=1*10/sup 19/ cm/sup -3/) subcollector with a 390-nm-thick InP collector doped at n=1.4*10/sup 16/ cm/sup -3/. The remaining epitaxy was grown by solid source MBE. >