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This paper describes state-of-the-art of high-speed electronic device and IC technologies for very high-speed lightwave communications systems. The technology of interest is for over 40-Gbit/s transmitter and receiver operations. Device technology including Si-Ge, GaAs-based, and InP-based heterostructure transistors as well as circuit design technology including analog/digital/mixed-signal and optoelectronic IC's are reviewed. The speed limiting factors are discussed to address the future trends toward 100 Gbit/s and beyond.

Transistor bandwidths are approaching terahertz frequencies. Paramount to high speed transistor operation is submicron device scaling. High bandwidths are obtained with heterojunction bipolar transistors by thinning the base and collector layers, increasing emitter current density, decreasing emitter contact resistivity, and reducing the emitter and collector junction widths. In mesa HBTs, minimum dimensions required for the base contact impose a minimum width for the collector junction, frustrating device scaling. We have fabricated HBTs with narrow collector junctions using a substrate transfer process. HBTs with submicron collector junctions exhibit extremely high f_max and high gains in mm-wave ICs. Transferred-substrate HBTs have obtained record 21 dB unilateral power gain at 100 GHz. Recently-fabricated devices have shown unbounded unilateral power gain from 40-110 GHz, and f_max cannot be extrapolated from measuremente. However, these devices exhibited high power gains at 220 GHz, the frequency limit of presently available microwave network analyzers. Demonstrated amplifier ICs in the technology include reactively tuned amplifiers at 175 GHz, lumped and distributed amplifiers with bandwidths to 85 GHz, and W-band power amplifiers.

A 2D hydrodynamic model based on modified Langevin forces for terminal current noise in the RF range is presented for Si and SiGe devices, where all transport and noise parameters are generated by full-band Monte Carlo simulations under bulk conditions and stored in lookup tables. Since these tables have to be built only once, the accuracy of the noise model is improved without increasing the CPU time compared to models based on analytical expressions for the parameters. The accuracy of the noise model is assessed by comparison with the Monte Carlo device model and good agreement of both models is found for diffusion and generation noise. The terminal current noise of a realistic SiGe HBT is investigated and it is found that hole diffusion noise has a strong impact on the collector current noise. The limitations of the thermodynamic model, a compact model for noise, are explored by comparison with the hydrodynamic model.

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.

This work presents multivariate regression polynomial as a versatile and efficient method for DC modeling of modern transistors with very different underlying physics including MOSFET (metal-oxide-semiconductor field-effect transistor), MESFET (metal–semiconductor field-effect transistor), HBT (heterojunction bipolar transistor), HEMT (High-electron-mobility transistor) and a novel silicon-on-insulator four-gate transistors (G⁴FET). A set of available data from analytic solution, TCAD simulation, and experimental measurements for different operating conditions is used to empirically determine the parameters of this model and a different set of test data is used to verify its predictive accuracy. The developed model expresses the drain current as a single multivariate regression polynomial with its validity spanning across different possible operating regions as long as the chosen independent variables lie within the range of training data set. The continuity of the resulting polynomial and its first and second order derivatives make it particularly suitable for implementation in a circuit simulator. The model also provides a method for further simplification based on prior knowledge of the underlying physical mechanism and shows excellent predictive capability for different kinds of devices. This can be very useful for modeling deep-submicron emerging devices for which any closed-form analytical solution is not yet available.

The difference between intensity interferometry and measurements of two-particle momentum correlations in heavy-ion collisions is discussed. These approaches are generally used to estimate the time-space scale of fireballs produced in heavy-ion collisions. It is inferred that the C(q_inv) function will increase with the decrease of q_inv for both bosons and fermions, if q_inv does not approach zero.

The Hanbury-Brown and Twiss (HBT) effects predict a Bose–Einstein enhancement of the two-particle momentum correlations of identical bosons at small relative momentum. However, the parallel momentum correlations between identical fermions are less argued. The momentum correlations can be altered by many factors, among which the spin interaction effects are discussed in this paper. It is found that the spin interaction plays an important role on the momentum correlations of identical fermions. For spin triplet state, a full Fermi–Dirac suppression represents as expected. On the contrary, a fake Bose–Einstein enhancement shows up for spin singlet state. The measured momentum correlations of fermions could hence provide some hints of spin interactions between them if all other factors such as Coulomb interactions were removed. Spin interactions make it more complicated to extract physical information from momentum correlations between fermions.

In the recent decades of high energy physics research, it was demonstrated that strongly interacting quark-gluon plasma (sQGP) is created in ultra-relativistic nucleus–nucleus collisions. Investigation and understanding of properties of the hadronic matter is among the important goals of NA61/SHINE collaboration at CERN SPS. Mapping of the phase diagram is achieved by varying the collision energy ($5\mathrm{\text{GeV}}<\sqrt{s_{\mathrm{\text{NN}}}}<17\mathrm{\text{GeV}}$) and by changing the collision system ($\mathrm{\text{p}}+\mathrm{\text{p}}$, $\mathrm{\text{p}}+\mathrm{\text{Pb}}$, $\mathrm{\text{Be}}+\mathrm{\text{Be}}$, $\mathrm{\text{Ar}}+\mathrm{\text{Sc}}$, $\mathrm{\text{Xe}}+\mathrm{\text{La}}$, $\mathrm{\text{Pb}}+\mathrm{\text{Pb}}$).

We report on the measurement of femtoscopic correlations in intermediate systems at intermediate SPS energies. Interpreting the results of measurements within the symmetric Lévy source formalism, we discuss the values of Lévy source parameters as a function of average pair transverse mass. One of the physical parameters is particularly important, the Lévy exponent $\alpha$, which describes the shape of the source and may be related to the critical exponent $\eta$ in the proximity of the critical point. Therefore, measuring it may shed light on the location of the critical endpoint of the QCD phase diagram.

Terahertz band has recently attracted the attention of the communication society due to its huge bandwidth and very high-speed wireless communications capability. It has been utilized in a variety of disciplines including physics, biology and astronomy for years; and the main concerns have always been obtaining highly efficient and high-power terahertz sources. Today, these problems are still the most important issues in establishing an operable wireless terahertz communication link. In this paper, recent studies in the field of terahertz source design are investigated based on the terahertz output power and efficiency. Solid-state sources and optical sources were comparatively reviewed with optical photoconductive material (OPM)-based methods which are combined with the terahertz antennas in the design phase generally. For wireless communication, the most suitable frequencies are between 0.3THz and 1THz due to the attenuation profile of the atmosphere. For this reason, based on the recently published studies, it has been observed that OPM and resonant tunneling diode-based sources are the most promising terahertz sources in terms of efficiency and power. Key issues and the main problems of terahertz photoconductive antennas which are the base of OPM method were also discussed in this paper.

Experimental studies on low frequency noise in bipolar junction transistors (BJT) including polysilicon emitter, hetero-junction bipolar transistors (HBTs) and silicon-germanium hetero-junction transistors (SiGe HBTs) are reviewed. The 1/f noise is treated in terms of mobility fluctuations. The validity of a new empirical relation between the 1/f noise corner frequency f_c (the frequency where the 1/f noise and shot noise are equal) and the peak cutoff frequency fr_peak is investigated. The experimental procedure to investigate the most dominant low-frequency noise source in the equivalent circuit is described. At medium frequencies, the white noise becomes dominant and the noise figure is calculated taking into account the emitter and base series resistance.

This work presents multivariate regression polynomial as a versatile and efficient method for DC modeling of modern transistors with very different underlying physics including MOSFET (metal-oxide-semiconductor field-effect transistor), MESFET (metal–semiconductor field-effect transistor), HBT (heterojunction bipolar transistor), HEMT (High-electron-mobility transistor) and a novel silicon-on-insulator four-gate transistors (G⁴FET). A set of available data from analytic solution, TCAD simulation, and experimental measurements for different operating conditions is used to empirically determine the parameters of this model and a different set of test data is used to verify its predictive accuracy. The developed model expresses the drain current as a single multivariate regression polynomial with its validity spanning across different possible operating regions as long as the chosen independent variables lie within the range of training data set. The continuity of the resulting polynomial and its first and second order derivatives make it particularly suitable for implementation in a circuit simulator. The model also provides a method for further simplification based on prior knowledge of the underlying physical mechanism and shows excellent predictive capability for different kinds of devices. This can be very useful for modeling deep-submicron emerging devices for which any closed-form analytical solution is not yet available.

Spatial-temporal properties of Δ(1232) resonance produced in double neutral pion photoproduction are investigated through HBT correlations of two identical pions. For this end, we develop a model in which the HBT correlations are measured in the reference frame of Δ at rest. A very preliminary result of the two pion correlation is obtained, showing the Gaussian radius of the intermediate resonance state (Δ (1232) dominant) is about 0.71±0.02 fm.

A 2D hydrodynamic model based on modified Langevin forces for terminal current noise in the RF range is presented for Si and SiGe devices, where all transport and noise parameters are generated by full-band Monte Carlo simulations under bulk conditions and stored in lookup tables. Since these tables have to be built only once, the accuracy of the noise model is improved without increasing the CPU time compared to models based on analytical expressions for the parameters. The accuracy of the noise model is assessed by comparison with the Monte Carlo device model and good agreement of both models is found for diffusion and generation noise. The terminal current noise of a realistic SiGe HBT is investigated and it is found that hole diffusion noise has a strong impact on the collector current noise. The limitations of the thermodynamic model, a compact model for noise, are explored by comparison with the hydrodynamic model.

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.

Transistor bandwidths are approaching terahertz frequencies. Paramount to high speed transistor operation is submicron device scaling. High bandwidths are obtained with heterojunction bipolar transistors by thinning the base and collector layers, increasing emitter current density, decreasing emitter contact resistivity, and reducing the emitter and collector junction widths. In mesa HBTs, minimum dimensions required for the base contact impose a minimum width for the collector junction, frustrating device scaling. We have fabricated HBTs with narrow collector junctions using a substrate transfer process. HBTs with submicron collector junctions exhibit extremely high f_max and high gains in mm-wave ICs. Transferred-substrate HBTs have obtained record 21 dB unilateral power gain at 100 GHz. Recently-fabricated devices have shown unbounded unilateral power gain from 40-110 GHz, and f_max cannot be extrapolated from measurements. However, these devices exhibited high power gains at 220 GHz, the frequency limit of presently available microwave network analyzers. Demonstrated amplifier ICs in the technology include reactively tuned amplifiers at 175 GHz, lumped and distributed amplifiers with bandwidths to 85 GHz, and W-band power amplifiers

This paper describes state-of-the-art of high-speed electronic device and IC technologies for very high-speed lightwave communications systems. The technology of interest is for over 40-Gbit/s transmitter and receiver operations. Device technology including Si-Ge, GaAs-based, and InP-based heterostructure transistors as well as circuit design technology including analog/digital/mixed-signal and optoelectronic IC's are reviewed. The speed limiting factors are discussed to address the future trends toward 100 Gbit/s and beyond.

Silicon-based devices, including the increasingly available SiGe-based devices, are now demonstrating f_T and f_MAX values over 200 GHz. These recent advances open the door to a wide range of silicon-based very high frequency, low power and highly integrated solutions. Trends in silicon MOS, SiGe HBT, SiGe MODFET and SiGe strained silicon FETs are reported. Silicon inroads to device functions viewed as the sole realm of III-V technologies are also being demonstrated. Capability and trends of the integrated silicon photodiode are reported here as an example. Integration of these high-speed devices into a complex circuit requires on-chip passive device functionality at such high frequency. Key devices to enable integration are the inductor, varactor, and transmission line, and operation of these devices at high frequency is reported. Further, we discuss noise isolation issues and techniques, which may be used when minimizing cross-talk within a conductive silicon substrate.

Using a 0.2-μm self-aligned epitaxial-growth silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technology, we have developed a chipset for 40-Gb/s time-division multiplexing optical transmission systems. In this paper, we describe seven analog and digital ICs: a 45-GHz bandwidth transimpedance amplifier, a 48.7-GHz bandwidth automatic-gain-controllable amplifier, a 40-Gb/s decision circuit, a 40-Gb/s full-wave rectifier, a 40-Gb/s limiting amplifier with a 32-dB gain, a 45-Gb/s 1:4 demultiplexer, and a 45-Gb/s 4:1 multiplexer. To increase bandwidth of the transimpedance amplifier, a common-base input stage is introduced. In order to have high gain and wide bandwidth simultaneously, active load circuits composed of a differential transimpedance amplifier are used for the AGC amplifier, the limiting amplifier, and the decision circuit. Full-rate clocking is employed to reduce the influence caused by clock-duty variation in digital circuits such as the decision circuit, the demultiplexer, and the multiplexer. All ICs were characterized by using on-wafer probes, and some of them were built in brass-packages for bit-error rate measurement.