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This work demonstrates an enhancement mode heterojunction bipolar p-FET (HEB-PFET) structure with a AlGaN/GaN heterojunction bipolar transistor (HBT) integrated on the drain side. Such device design notably contributes to the ultra-high output current density, which is conventionally limited by the low hole mobility and concentration in the p-FETs. The HEB-PFET exhibits an output current density of 241 mA/mm, which is 134 times larger compared to the conventional p-FET (C-PFET) and 2.4 times of the homojunction bipolar p-FET (HOB-PFET). This can be attributed to a better current gain of HBT than homojunction bipolar transistor (BJT). An optimized HEB-PFET of 6 nm p-GaN layer beneath the gate is proposed, where ION/IOFF is >1011, and Vth is −0.44 V. Additionally, thermal stabilities are studied with temperature changes from 300 K to 425 K. Moreover, a semi-empirical compact model is presented to visually explain the working principle of the HEB-PFET. [ABSTRACT FROM AUTHOR]

Within many years microelectronics developed based on p-n junctions made of germanium or silicon, namely on homojunctions (BJT). In this case the main technological difficulty was to control the level of doping concentrations. Semiconductor structures were obtained by the variation of type and concentration of the doping impurities. A new phase of the evolution of the semiconductor devices is the manufacturing and large scale using of heterojunctions. Heterojunction is the contact of two semiconductors, different according to the chemical composition, existing in a single crystal. Within this contact not only the energetic areas structure varies, but also the effective body of the carriers, their mobility and other parameters. The possibility of variation of these parameters allows the manufacture of unique devices that have record performance. Heterojunction bipolar transistors (HBT) have the following benefits: static gain in current, high cutting frequency, high speed of conversion, low temperature running. The aim of my study is transit time study through the base in case of drift transistors. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the DC parameter extraction of the equivalent circuit model in an InP-InGaAsSb double heterojunction bipolar transistor (HBT). The non-ideal collector current is modeled by a non-ideal doping distribution in the base region. Then several consequent non-ideal effects, which have always been neglected in typical HBTs, are studied using Medici device simulator. Moreover, the associated DC parameters of VBIC model are extracted accordingly. The equivalent circuit model is in good agreement with the measured data in IC –VCE characteristics. [Copyright &y& Elsevier]

This paper presents a novel hardware reconfiguration technique implemented in a dual integrated-circuit (IC) GaAs HBT power amplifier (PA) design and demonstrates reduced current and improved efficiency at low power. The method automatically reconfigures the hardware of an RF IC PA over a given power transmission. Hardware interfacing and synchronization from outside the PA is minimized, and automatic gain compensation upon hardware reconfiguration is achieved with minimal temperature-dependant calibration. The challenge of integrating such complex on-chip hardware functions in a GaAs HBT technology was circumvented by the introduction of a gating concept used in conjunction with envelope feedback, and careful tradeoffs between circuit complexity and performance. Designs that suit the on-chip integration of the technique in GaAs HBT or Si bipolar junction transistor technologies are described. Experimental data are reported to support the proposed method. [ABSTRACT FROM PUBLISHER]

In this paper, the design and analysis of two novel high robustness RF electrostatic discharge (ESD) protection are proposed in GaAs 2-\mu\ m HBT process. One incorporates with the ESD devices to form a bandpass filter structure with good impedance matching, which has eight discharging paths. The other is fabricated with parasitic capacitance reduction technique for the ESD protection, and has four discharging paths. These two protection circuits are also applied to 5.8-GHz amplifiers for demonstration. In the meanwhile, two amplifiers without ESD protection and with conventional ESD protection are fabricated in parallel for comparison. Based on the measurement results, it indicates that the two proposed ESD-protected amplifiers feature much higher ESD robustness and better RF performance than the conventional design. [ABSTRACT FROM AUTHOR]

We investigate the efficacy of mitigating radiation-based single event effects (SEE) within circuits incorporating SiGe heterojunction bipolar transistors (HBTs) built with an N-Ring, a transistor-level layout-based radiation hardened by design (RHBD) technique. Previous work of single-device ion-beam induced charge collection (IBICC) studies has demonstrated significant reductions in peak collector charge collection and sensitive area for charge collection; however, few circuit studies using this technique have been performed. Transient studies performed with Sandia National Laboratory's (SNL) 36 MeV ^16O microbeam on voltage references built with N-Ring SiGe HBTs have shown mixed results, with reductions in the number of large voltage disruptions in addition to new sensitive areas of low-level output voltage disturbances. Similar discrepancies between device-level IBICC results and circuit measurements are found for the case of digital shift registers implemented with N-Ring SiGe HBTs irradiated in a broadbeam environment at Texas A&M's Cyclotron Institute. The error cross-section curve of the N-Ring based register is found to be larger at larger ion LETs than the standard SiGe register, which is clearly counter-intuitive. We have worked to resolve the discrepancy between the measured circuit results and the device-level IBICC measurements, by re-measuring single-device N-Ring SiGe HBTs using a time-resolved ion beam induced charge (TRIBIC) set-up that allows direct capture of nodal transients. Coupling these measurements with full 3-D TCAD simulations provides complete insight into the origin of transient currents in an N-Ring SiGe HBT. The detailed structure of these transients and their bias dependencies are discussed, together with the ramifications for the design of space-borne analog and digital circuits using SiGe HBTs. [ABSTRACT FROM AUTHOR]

Abstract: This paper demonstrates a concise and novel voltage-controlled multiple-valued logic (MVL) design using the standard BiCMOS technique. This MVL circuit is constructed by a voltage-controlled negative differential resistance (NDR) circuit, which is integrated by the standard Si-based metal–oxide-semiconductor field-effect-transistor (MOS) and SiGe-based heterojunction bipolar transistor (HBT). There exists a two-peak current–voltage curve by connecting two integrated MOS–HBT–NDR elements in parallel as we suitably determine the width/length (W/L) of the MOS devices. In particular, each peak current can be effectively modulated by the corresponding controlled voltage. Using this special characteristic, we can obtain the three logic states with arbitrary sequence at the output. [ABSTRACT FROM AUTHOR]

GaAs/AlGaAs heterojunction bipolar transistors (HBTs) have attracted much attention because of their high-speed performance. However, long-term operation seriously degrades the device characteristics: the current gain decreases and the low-bias-leakage current increases. This degradation has long been an issue in GaAs-based devices operated under minority-carrier injection, such as laser diodes. The cause of degradation is thought to lie in the carbon-doped base, but this is not yet certain. In this paper the degradation of HBTs is described, especially that of GaAs/AlGaAs HBTs with a heavily carbon-doped base layer. Two types of device degradation are found, namely, hydrogen-related degradation and carbon-related degradation. The mechanisms governing the degradation are discussed in the framework of the recombination-enhanced defect reaction (REDR) and charge state effect (CSE). © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(5): 33–41, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10208 [ABSTRACT FROM AUTHOR]

Abstract: Use of the Pd/Ge/Cu multilayers as the emitter and collector ohmic metal for the fully Cu-metallized InGaP/GaAs heterojunction bipolar transistors is studied. The Pd/Ge/Cu ohmic contact exhibited a very low contact resistance of 5.73×10−7 Ωcm2 at a low annealing temperature (250°C) and the microstructure evolution of Pd/Ge/Cu ohmic contact was investigated using transmission electron microscopy and energy dispersive spectrometer. We also did some comparisons between the Pd/Ge/Cu, Pd/Ge/Ti/Pt/Cu, and the traditional Au/Ge/Ni/Au ohmic contact structures to n-type GaAs. The common emitter I–V curves and Gummel plot of these Cu-metallized HBTs using Pd/Ge/Cu ohmic contact and Cu interconnects showed similar electrical characteristics as those HBTs with conventional Au-metallization. The cutoff frequency (f T) of 3×20-μm-emitter-area devices was about 38GHz. During both the current-accelerated stress test (110kA/cm2 stress for 24h) and the thermal stability test (annealing at 250°C for 24h), the fully Cu-metallized HBT with Pd/Ge/Cu ohmic contact and Cu interconnects showed almost no obvious degradation in electrical characteristics. The results show that the Pd/Ge/Cu ohmic contact in combination with the Cu interconnects can be used on HBT devices to achieve the Au-free fully Cu-metallized InGaP/GaAs HBTs, and the devices exhibit good device performance. [Copyright &y& Elsevier]

Abstract: Two new germanium profiles, graded double box (GDB) and graded step box (GSB), are considered in the base region for an n–p–n silicon–germanium heterojunctions bipolar transistors (SiGe HBTs). Their effects on the performance of the HBT-based common emitter amplifier circuit are investigated so as to predict the behavior of analog circuits in the high-frequency region. An analytical model of an n–p–n SiGe HBT with uniform impurity doping in the base is described, and used to extract SPICE parameters for the devices based on GDB and GSB as well as other two accepted profiles i.e. box and triangular profiles. The frequency response, current gain roll-off and gain-bandwidth product of HBT-based common emitter amplifier circuit for all the four profiles have been compared and contrasted. [Copyright &y& Elsevier]

We investigate radiation-induced effects on the DC, AC and thermal characteristics of high-performance SiGe HBTs fabricated on thin-film SOI. TCAD simulations indicate novel heavy-ion charge collection phenomena resulting from the unique CBEBC device layout of this technology platform. [ABSTRACT FROM PUBLISHER]

Device-level current transients are induced by injecting carriers using two-photon absorption from a subbandgap pulsed laser and recorded using wideband transmission and measurement equipment. These transients exhibit three distinct temporal trends that depend on laser pulse energy as well as the transverse and vertical charge generation location. The nature of the current transient is controlled by both the behavior of the subcollector-substrate junction and isolation biasing. However, substrate potential modulation, due to deformation of the subcollector-substrate depletion region, is the dominant mechanism affecting transient characteristics. [ABSTRACT FROM PUBLISHER]

Abstract: Incorporation of high doping concentrations and the creation and maintaining of steep doping profiles during processing are key enabler for high level RF performance of heterojunction bipolar transistors (HBTs). In this paper, we discuss results of base doping and dopant profile control for npn and pnp SiGe HBTs fabricated within 0.25μm BiCMOS technologies. High level of electrically active B and P doping concentrations (up to 1020 cm−3) have been incorporated into SiGe. By adding C to SiGe steep doping profiles have been maintained due to the prevention of dopant diffusion during device processing. It is shown that broadening of P doping profiles caused by segregation could be reduced by lowering the deposition temperature for the SiGe cap. B and P atomic layer doping is shown to be suitable for the creation of steep and narrow doping profiles. This result is demonstrating the capability of the atomic layer processing approach for future devices with critical requirements of dopant dose and location control. [Copyright &y& Elsevier]

Abstract: In this paper, we present the design and analysis of a proposed single heterojunction bipolar transistor (HBT)-based photoreceiver front-end configuration. This configuration uses a single heterojunction bipolar transistor for both photodetection and amplification purpose. The analysis of the proposed optoelectronic integrated circuit (OEIC) receiver configuration has been carried out and performance characteristics have been determined for an InP/InGaAs HBT receiver for operation in 1.55μm wavelength region. The proposed receiver has a reasonable sensitivity along with a high transimpedance gain and large bandwidth comparable to contemporary optical receivers based on separate detector and amplifier. Use of a single HBT in the front-end would greatly simplify the fabrication of optoelectronic integrated circuit (OEIC) receiver in the monolithic form. [Copyright &y& Elsevier]

Abstract: The present paper focuses on solutions of the experimental difficulties rising up when a full low frequency noise characterization of bipolar transistors exhibiting high noise levels and low input dynamic input impedances is carried out using a direct characterization technique. First, a typical direct characterization experimental set-up is introduced pointing out the difficulties to be faced when a high noise, low input impedance transistor is addressed. Then, an improved version of the experimental set-up is proposed and successfully applied to AlGaAs/GaAs heterojunction bipolar transistors. [Copyright &y& Elsevier]

We have successfully designed and fabricated a high-bit-rate low-power decision circuit using InP-InGaAs heterojunction bipolar transistors (HBTs). Its main design feature is the use of a novel master-slave D-type flip-flop (MS-DFF) as the decision circuit core to boost the operating speed. We achieved error-free operation at a data rate of up to 60 Gb/s using an undoped-emitter InP-InGaAs HBT with a cutoff frequency fT of approximately 150 GHz and a maximum oscillation frequency fmax of approximately 200 GHz. Our decision circuit operates approximately 15% faster than one with a conventional MS-DFF core. We also achieved 90-Gb/s operation with low power consumption of 0.5 W using an InP-InGaAs DHBT exhibiting fT and fmax of 232 and 360 GHz, respectively. These results demonstrate that InP-based HBTs and our novel MS-DFF are attractive for making ultrahigh-performance ICs for future optical communications systems operating at bit rates of 100 Gb/s or more. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive comparison of three state-of-the-art heterojunction bipolar transistors (HBTs); the AlGaAs/GaAs HBT, the Si/SiGe HBT and the InGaAs/InP HBT. Our aim in this paper is to find the potentials and limitations of these devices and analyze them under common Figure of Merit (FOM) definitions as well as to make a meaningful comparison which is necessary for a technology choice especially in RF-circuit and system level applications such as power amplifier, low noise amplifier circuits and transceiver/receiver systems. Simulation of an HBT device with an HBT model instead of traditional BJT models is also presented for the AlGaAs/GaAs HBT. To the best of our knowledge, this work covers the most extensive FOM analysis for these devices such as I–V behavior, stability, power gain analysis, characteristic frequencies and minimum noise figure. DC and bias point simulations of the devices are performed using Agilent''s ADS design tool and a comparison is given for a wide range of FOM specifications. Based on our literature survey and simulation results, we have concluded that GaAs based HBTs are suitable for high-power applications due to their high-breakdown voltages, SiGe based HBTs are promising for low noise applications due to their low noise figures and InP will be the choice if very high-data rates is of primary importance since InP based HBT transistors have superior material properties leading to Terahertz frequency operation. [Copyright &y& Elsevier]

This paper presents a new InP HBT structure with a collector pedestal under the HBT''s intrinsic region by using selective ion implantation and MBE regrowth. This is the first such structure reported in III–V HBTs. Our results exhibit excellent DC performances including high current gain, low base–collector leakage current, and low collector access resistance. One-hundred and seventy gigaHertz ft and 130 GHz fmax were obtained. The RF performances were found to be limited by the regrowth interface charge accumulation. This is expected to be overcome by using compensating p-doping at the regrowth interface. [Copyright &y& Elsevier]

We present an overview of radiation effects in silicon-germanium heterojunction bipolar transistors (SiGe HBT). We begin by reviewing SiGe HBTs, and then examine the impact of ionizing radiation on both the dc and ac performance of SiGe HBTs, the circuit-level impact of radiation-induced changes in the transistors, followed by single-event phenomena in SiGe HBT circuits. While ionizing radiation degrades both the dc and ac properties of SiGe HBTs, this degradation is remarkably minor, and is far better than that observed in even radiation-hardened conventional Si BJT technologies. This fact is particularly significant given that no intentional radiation hardening is needed to ensure this level of both device-level and circuit-level tolerance (typically multi-Mrad TID). SEU effects are pronounced in SiGe HBT circuits, as expected, but circuit-level mitigation schemes will likely be suitable to ensure adequate tolerance for many orbital missions. SiGe HBT technology thus offers many interesting possibilities for space-borne electronic systems. [ABSTRACT FROM AUTHOR]

It is necessary to take quantum effects into account in the design of nanometer-scale high electron mobility transistors (HEMTs) and heterojunction bipolar transistors (HBTs). To achieve this, an effective potential method is applied to drift-diffusion (DD)-based simulations of the threshold-voltage characteristics of nanometer-scale InP-based HEMTs and to ensemble Monte Carlo (EMC) simulations of transit times in InP-based HBTs. The simulated results are compared with the experimental results in order to validate the method. We conclude that device simulations incorporating the effective potential method are very useful for designing millimeter-wave HEMTs and HBTs. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14: 283–289, 2004. [ABSTRACT FROM AUTHOR]

Neutron, proton, and electron irradiation effects In InGaP/GaAs single heterojunction bipolar transistors are investigated. Devices with different emitter sizes and grown by two different growth techniques are studied. At low fluences of proton and neutron irradiation, a small gain increase is observed at low base currents. At higher fluences, gain degradation is observed whose magnitude depends on the nature and fluence of the irradiation particle. In the case of electron irradiation, the change in pin is veer small for electron fluence up to 7 × 1015 e/cm² although a careful analysis shows a slight gain increase at low base currents and a slight gain degradation at higher base currents. The gain increase at small base currents. and low fluence is believed to be caused by the ionization damage in the polyimide passivation layer. The gain degradation at higher fluence and high base currents is due to the displacement damage in the emitter-base junction region. In addition to the gain degradation, neutron irradiation causes a shift of the emitter-base offset voltage, which is caused by the displacement damage in the base-collector region. The correlation of the gain degradation coefficients for the different particles is discussed in the framework of the NIEL theory. [ABSTRACT FROM AUTHOR]

In this paper we discuss a design methodology we used to fabricate a 100-GHz-band monolithic oscillator that power-combines four heterojunction bipolar transistor (HBT) based suboscillators, and the experimental results we obtained. We analyzed the oscillation condition by considering the loop gain when feedback is present, and adjusted the design parameters so as to combine the output powers of four suboscillators by making them oscillate in phase. The active elements we used for the suboscillators were InGaP/InGaAs HBTs with emitter dimensions 1.0 µm × 5.0 µm, for which fT and fmax were 190 and 240 GHz, respectively. The signal frequency of the completed oscillator was 97. 4 GHz, its output power +3.0 dBm. The biases on the HBTs were IC = 10 mA and VCE = 2.0 V. In order to discuss the power combining efficiency, we fabricated test oscillators with only one and dual power combined oscillators, which were investigated under the same measurement conditions. These circuits oscillated at 100.5 and 100.4 GHz, respectively, with -3.2 and -0.4 dBm output powers. These results confirm that the output power increases with the number of suboscillators. As far as we know, our article is the first to report a monolithic oscillator that power-combines four suboscillators. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(6): 13–22, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10003 [ABSTRACT FROM AUTHOR]

Mixed mode circuit and device simulation has been used to investigate the linearity properties––harmonic distortion of high-speed low voltage SiGe heterojunction bipolar transistors (HBTs). The simulation test-circuit included the active device, modeled by finite element simulation, as well as passive elements in a SPICE circuit for DC-feed and AC-coupling of the RF-signal. Different Ge-profiles for reduced harmonic distortion have been investigated and compared to a conventional high-speed graded Ge-profile. To find an optimized Ge-profile for RF-applications other figure-of-merits, such as maximum cut-off frequency and minimum noise figure were also simulated. Using the same mixed mode simulation approach the design of the epitaxial collector doping profile for high breakdown voltage, high cut-off frequency and reduced harmonic distortion was investigated. [Copyright &y& Elsevier]

In this paper we investigate the impact of interface charges at heterojunctions on the performance of heterostructure bipolar transistors (HBT). Interface charges can modify the limiting process for the carrier transport in a device. Therefore, intentional interface charges introduced by δ-doped layers are basic tools for interface engineering. An accurate modelling of heterointerfaces which includes thermionic-field emission, surface charges, and surface dipoles allows to analyse the electrical performance of some modern devices based on band gap and interface engineering. It is demonstrated that the limiting transport process at an abrupt heterojunction can be shifted from thermionic emission towards drift-diffusion due to the presence of interface charges. We will also show that controlling the number and polarity of interface charges enables to improve HBT device performances. [Copyright &y& Elsevier]

We have fabricated graded-GaAsP-base HBTs with InGaP emitters for the first time. Compared with the uniform-GaAs-base HBTs, current gain increased by a factor of 2 due to built-in field in the graded base. [ABSTRACT FROM AUTHOR]

The sensitivity of heterojunction-bipolar-transistor -- (HBT-) based OEIC receivers with metal-semiconductor metal photodetectors (MSM-PD) or p-i-n photodetectors (p-i-n-PD) are compared. With an accurate small-signal circuit model of an InP/InGaAs HBT, it is shown that sensitivity of the p-i-n-HBT receiver is higher than that of the MSM-HBT receiver even though the high-frequency equivalent input noise current density is higher for the former than the latter. However, the HBT receiver using MSM-PD with light transparent conducting fingers would offer a potential sensitivity improvement of 0.5 dB over the p-i-n--HBT receiver at 10 Gbit/s due to an increased responsivity of the MSM-PD. [ABSTRACT FROM AUTHOR]

A new nonlinear empirical model that can be applied to the collector current source of power HBT devices and to the drain current source of power MESFETs is presented. The model includes the self-heating effects present in both HBT and MESFET devices. It also accurately predicts the slope variation of the dc-I-V characteristics from positive to negative, which occurs in MESFET devices. The proposed model is validated with the measured dc and small-signal characteristics of one HBT and one MESFET medium-power device. Good agreement between measurement and simulation results was obtained for both devices. [ABSTRACT FROM AUTHOR]

A novel ballast resistor network is proposed to achieve a better thermal management in HBT power cells without degrading the RF performances. Experiments were conducted on two HBT power amplifiers. They occupy same area. One is designed using conventional ballast network. The other uses proposed novel network. Temperature comparisons were made based on the same current density. Infrared camera images show that a more uniform temperature distribution is obtained in novel ballast network power amplifier. Our results demonstrate that the proposed novel ballast network has promising applications in high power amplifiers. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 711–713, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23174 [ABSTRACT FROM AUTHOR]

Abstract: In this study, a detailed characterization on the microwave noise performance of high gain metamorphic heterojunction bipolar transistor (MHBT) in the temperature range of 300 K to 380 K is performed. The results are compared between the MHBT and the referenced lattice-matched InP HBT (LHBT) devices. The minimum noise figure (NFmin) versus frequency in the range of 2 to 20 GHz at different temperatures for a 1.6×20 μm2 HBTs are measured. The experimental results show that the MHBT exhibits a slightly larger variation in NFmin compared to lattice-matched HBTs. Even though the MHBTs may have much higher thermal resistance, this may not significantly affect the device microwave noise performance. [Copyright &y& Elsevier]

A conventional formula for the total emitter-to-collector transit time (τec) or the short circuit current gain cut-off frequency (fT) in heterojunction bipolar transistor (HBT) has been modified to include the effects of the intrinsic emitter dimensions (width, length, area) and the extrinsic parasitic components. The formula shows how the emitter dimensions and the device parasitics affect the total transit time and fT. The validity of the formula has been verified experimentally for the case of InP/InGaAs HBTs with polyimide planarization process. [Copyright &y& Elsevier]