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The InP/GaAsSb/InP DHBT (Double Heterojunction Bipolar Transistor) has demonstrated superior high-frequency performance and is attractive for next generation's microwave electronics due to its inherently low bandgap base material GaAsSb, high electron speed in collector material InP, and type-II band lineup at the base-collector heterojunction. This work studied the GaAsSb material properties, advanced the InP-based GaAsSb DHBT device technology, and developed related high-speed/high-power microwave integrated circuits for the first time. The material study of this work focused on proper characterizations of GaAsSb material and GaAsSb DHBT device structures. Various techniques using photoluminescence, X-ray diffraction, low-angel incident X-ray refraction, and Hall measurement were deployed. The device study focused on implementing a reliable fabrication process flow of GaAsSb DHBT devices, and characterizing the devices in terms of power gain, output compression, and circuit matching properties. Novel self-aligned emitter etch steps were proposed and resulted in uniform device topology and performance. InP/GaAsSb/InP DHBT devices with 1x10mum2 emitter-size demonstrated a maximum fT of 132GHz and fmax of 105GHz. Microwave power density as high as 1.9mW/mum2 at 5GHz was also demonstrated and confirmed the suitability of GaAsSb DHBTs in simultaneous high-frequency and high-power circuit applications. The first-generation low-power/low-noise transimpedance amplifiers with the state-of-the-art performance were demonstrated. The first InP/GaAsSb/InP DHBT MMIC (Monolithic Microwave Integrated Circuit) oscillator at Ka-band was also developed in this work. Future studies on GaAsSb material growth will be continued using additional characterization techniques. Device process optimizations, DC gain degradation at emitter-base junction, and scalable small-signal/large-signal device models will be addressed. Finally, further improvement and explorations of various high-speed/high-power MMICs are expected using InP-based GaAsSb DHBT devices.

The work described in this thesis is to develop a complete SiGe MMIC process. This includes a reliable, high yield and easy to process SiGe MMIC fabrication technology, with integrated passive models to allow for accurate circuit design. Heterostructure design and transistor geometry design are utilized to demonstrate power SiGe HBTs and MMIC amplifiers. With the development of the three novel self-aligned SiGe HBT/MMIC processes, I have demonstrated an optimization approach to obtain reliable, high yield and easy to process MMIC circuits. The different processes are also compared in terms of performance and cost. HBT-PT1 is optimized to achieve simple photomask alignment, with the least stringent processing requirements. The other process namely HBT-PT2 is the best general purpose process since there are no limitations in terms of metal thicknesses. This process is also less costly as the number of masks and therefore fabrication steps are minimized. The last process known as HBT-PT3 is the process of choice for the best performing HBTs with reduced parasitics from the contact pads. Integrated passive components such as inductors and capacitors fabricated in the MMIC process are of interest and their compact modeling have been studied in this thesis. By introduction of novel inductor and capacitor structures to achieve high quality factor, Q, it is imperative to develop a general design methodology to model such components as it is rather difficult to develop general design equations for them. These design equation if available are generally not very accurate. The alternatives to these design equations are electromagnetic simulations or experimental S parameter measurements which are useful for the initial design/foundry setup stage. However, with the maturity of the process, designers would require compact circuit models that enhance designer's intuition and allow for design flexibility. Compact models will also simplify transient analysis and allow embedding of the parasitics into the matching network design. The two compact models for the capacitor and inductor that have been developed in this thesis are based on fundamental transmission lines, are scalable from narrowband to wideband and are the first compact models, to the authors' knowledge, that systematically fit the frequency response beyond the first resonance. (Abstract shortened by UMI.)

The immense demand for communication systems world wide has created an enormous market for semiconductors devices in variegated applications. While scaled CMOS is consolidating its stronghold in the analog and RF domains, the wide gamut of microwave frequencies is being competed for by the various types of III-V heterojunction based semiconductor devices, which were made amenable to high-volume production, thanks to rapid improvements in bulk-processing and fabrication techniques in the last decade. Among these devices, the quest for faster, more powerful and low cost transistors has led researchers to investigate innovative topologies. The availability of powerful CAD tools that incorporate the most intricate physical phenomenon in the modeling process has provided a much needed impetus to this ongoing research. Of the scores of disparate devices that have been investigated, Heterojunction Bipolar Transistors (HBTs) have carved a niche for themselves owing to their high speeds and greater power handling capabilities. In this work, the design of an innovative HBT with a collector-up topology, i.e., with the collector situated on top of the device and emitter on the substrate side, is carried out and optimized for maximizing the high frequency performance. The material system used here is Ga x In 1-x P/GaAs (with x=0.51 indicating lattice matched composition), which has relatively superior material properties and etching characteristics than the conventional Al x Ga 1 -xAs/GaAs material system. The material properties of the ternary were investigated and the most suitable values were ascertained through meticulous research. These parameters, along with the mobility models (that were derived by investigating published results), were made compatible to an emitter-up HBT and incorporated into a two dimensional, physically-based, numerical simulator called ATLAS by Silvaco Inc. The motive was to verify the correctness of the material parameters and models derived. The simulation results compared favorably with the published results. With these verified material parameters and mobility models, a collector-up GaInP/GaAs HBT structure with unetched extrinsic emitter was simulated. After a performance appraisal with the emitter-up structure, the impact of having an undercut in the extrinsic base region was investigated. It was found that this undercut drastically improved the high frequency performance as well as DC characteristics of the collector-up structure. This was documented by a significant increase in cutoff frequency (f T ) from 109 GHz to 140 GHz. It was even more pronounced in maximum frequency of oscillation (f max ), which is more practically useful than cutoff frequency, from 76 GHz to 233 GHz. These simulation results are much better than the practically experimented values. The high frequency parametric values described here were achieved after scrupulously optimizing the collector-up HBT structure. Towards the end of the thesis, two promising collector-up structures with completely etched extrinsic emitters were simulated and their performance compared with the first collector-up HBT structure.

The improvement of high speed and high power performance of self-aligned GaInP/GaAs Heterojunction Bipolar Transistors (HBTs) by means of various layer designs such as tunneling emitter, electron launcher designs and double HBTs is studied. The realization of broadband, high-bit-rate transimpedance amplifiers using optimized devices for near future optical telecommunication systems is also addressed. Optimization of ohmic contact and passive elements was carried out. A fabrication technology was developed for Microwave Monolithic Integrated Circuits (MMICs). This was accomplished by a simple wet etching technology combined with Lateral Etching Undercut (LEU). A tunneling emitter, a composite emitter and a double HBT design with optimized collector spacer were studied for improving the high speed performance. These designs showed fT and fmax values up to 60GHz and 100 GHz which are comparable with other published GaInP/GaAs HBT results. The collector-emitter offset voltage (Voffset) of GaInP/GaAs HBTs was studied using Ni/Ge/Au and Ti/Pt/Au collector contact metals. Experimental and theoretical investigations were conducted to find the Voffset dependence on collector metal barrier; A passivation process was developed to prevent degradation of the device. DC and RF performance before and after passivation were then compared to evaluate its impact. Various monolithic transimpedance amplifiers were designed, fabricated, and successfully tested based on information obtained from studies of individual active and passive components in terms of circuit topology, high gain and broad band performance. These circuits show a transimpedance gain of up to 47dBO with bandwidth of over 25 GHz and operation rate of 10Gb/sec. Finally, power characterization of various HBTs were conducted and the impact of collector metal, ballast emitter resistor was studied. High power density performance is reported using GaInP/GaAs HBTs grown by Chemical Beam Epitaxy (CBE) technology. A maximum power of 1.08 W (5.4 W/mm) using 10 finger 2 x 20 mum2 GaInP/GaAs HBTs was found under class B operation.

AlGaAs/GaAs HBTs with similar DC and microwave performance and different low-frequency noise and reliability characteristics were studied. The low-frequency base noise was correlated to the HBT long term reliability, due to the fact that both base noise and degradation mechanisms had the same origin. The HBTs with high degree of reliability showed a record high lifetime of 10 9 hours at 120°C junction temperature, while their base noise showed a minimum of 3 x 10-20A 2/Hz at 10Hz, which is the lowest reported value for AlGaAs/GaAs devices. Next, a general theory for low-frequency noise in semiconductor devices was developed, which can explain any measured noise characteristics that could not be explained with previous noise theories. This theory suggests that the low-frequency noise is an integral of many carrier trapping and de-trapping from a continuum of traps within the bandgap, of the semiconductor. The presented theory, unlike previous theories, does not require a specific lifetime probability function and can explain high lifetime values required for 1/f noise characteristics observed at very small frequencies. CBE grown GaInP/GaAs HBTs developed at the University of Michigan were characterized and modeled using a high-frequency noise model developed here. A minimum noise figure of 2.65dB with an associated gain of 12.5dB, at 8GHz was achieved for optimum geometry (2 x 30mum2) HBT. Analysis of the model showed the importance of base and emitter access resistances, shot noise sources and base-emitter incremental resistance on high-frequency noise. The same devices were also studied for their power and linearity characteristics, and showed the highest reported output power density of 3.48mW/mum 2 for GaInP/GaAs HBTs. Furthermore, a 10 finger 2 x 20mum 2 HBT achieved 1.08Watt CW output power at 8GHz. The GaInP/GaAs HBTs were also used in microwave monolithic amplifiers. A high-gain dual-feedback amplifier with a gain of 18.8dB and a bandwidth of 13.5GHz achieved the highest reported gain-bandwidth product among GaAs based HBT amplifiers. Moreover the design methodology of high gain HBT distributed amplifiers was investigated and showed the importance of base and collector resistances on amplifier gain. Based on the results, a 3-stage attenuation-compensated distributed amplifier with a gain of 12.7dB over a bandwidth of 27.5GHz was fabricated and tested.