Active Semiconductor Devices Research Articles

Cyclostationary noise modeling of radio frequency devices

SummaryWe present a review of the current status of research in the modeling and simulation of cyclostationary (nonlinear) noise properties of semiconductor active devices operated in forced large‐signal conditions, a typical operating regime for high‐frequency applications. We discuss both the case of physics‐based device simulations, where numerical burden is the most important issue, and the derivation of compact cyclostationary noise models. In the latter case, both phenomenological amplitude modulation approaches and the derivation of consistent analytical device descriptions are discussed. We show examples of both physics‐based simulations of the noise properties of a realistic high‐electron mobility transistor resistive mixer and show for the first time the application of a novel, fully analytical cyclostationary noise bipolar transistor model. Copyright © 2014 John Wiley & Sons, Ltd.

Enhanced Fluorescence Emission from Silicon-Rich Nitride Guided Mode Resonance Gratings

A one-dimensional subwavelength grating structure is used to enhance the emission from Si nanocrystals embedded in silicon-rich nitride film. The enhancement is attributed to guided-mode resonance effects supported by subwavelength gratings. Both the reflection and photoluminescence experiments are presented aimed at acquiring guided mode spectrum and the emission enhancement factor. A ten-fold enhancement of the fluorescence emission by Si nanocrystals is obtained at the low group velocity band edge of subwavelength gratings. Our results indicate that silicon-rich nitride is a suitable material for the fabrication of high efficiency light emitting structures. The versatility of silicon-rich nitride material system has a far-reaching significance for the realization of optically active complementary metal oxide semiconductor devices.

Analysis, Design, and Experimental Results of Novel Snubberless Bidirectional Naturally Clamped ZCS/ZVS Current-Fed Half-Bridge DC/DC Converter for Fuel Cell Vehicles

This paper presents a novel snubberless naturally clamped bidirectional current-fed half-bridge isolated dc/dc converter for fuel cell vehicles (FCVs). The proposed converter achieves zero-current switching (ZCS) of the primary-side active semiconductor devices and zero-voltage switching of the secondary-side active semiconductor devices. It is a potential topology for FCVs, front-end dc/dc power conversion for fuel cell inverters, and energy storage. A proposed secondary-modulation clamps the voltage across the primary-side devices (current fed) naturally and eliminates switch turn-off voltage spike concern with ZCS without any additional circuit. This leads to reduced footprints and lower cost. Voltage across the primary-side current-fed devices is independent of duty cycle like conventional current-fed converters but clamped at a reflected output voltage. Therefore, comparatively low-voltage-rating devices with a low on-state resistance are used, introducing low conduction losses and higher efficiency. Steady-state analysis, operation, design, simulation, and experimental results of the proposed converter are reported in this paper.

Characterization of large volume 3.5″×8″ LaBr3:Ce detectors

The properties of large volume cylindrical 3.5″×8″ (89mm×203mm) LaBr3:Ce scintillation detectors coupled to the Hamamatsu R10233-100SEL photo-multiplier tube were investigated. These crystals are among the largest ones ever produced and still need to be fully characterized to determine how these detectors can be utilized and in which applications. We tested the detectors using monochromatic γ–ray sources and in-beam reactions producing γ rays up to 22.6MeV; we acquired PMT signal pulses and calculated detector energy resolution and response linearity as a function of γ-ray energy. Two different voltage dividers were coupled to the Hamamatsu R10233-100SEL PMT: the Hamamatsu E1198-26, based on straightforward resistive network design, and the “LABRVD”, specifically designed for our large volume LaBr3:Ce scintillation detectors, which also includes active semiconductor devices. Because of the extremely high light yield of LaBr3:Ce crystals we observed that, depending on the choice of PMT, voltage divider and applied voltage, some significant deviation from the ideally proportional response of the detector and some pulse shape deformation appear. In addition, crystal non-homogeneities and PMT gain drifts affect the (measured) energy resolution especially in case of high-energy γ rays. We also measured the time resolution of detectors with different sizes (from 1″×1″ up to 3.5″×8″), correlating the results with both the intrinsic properties of PMTs and GEANT simulations of the scintillation light collection process. The detector absolute full energy efficiency was measured and simulated up to γ-rays of 30MeV

Numerical modeling of MOS transistor with interconnections using lumped element-FDTD method

A detailed three-dimensional (3-D) full-wave time-domain simulation model is presented for the analysis of an active semiconductor device. Microwave analysis of the nMOS transistor using monolithic microwave integrated circuit (MMIC) is simulated. A three-dimensional finite-difference time-domain (3D-FDTD) scheme is adopted to describe the circuit passive part, whereas numerical device simulation techniques are employed for the active semiconductor devices. The proposed algorithm provides the time and space distribution of the unknown functions electrostatic potential, carriers' concentration, and current density for the MOS transistor. Fast Fourier transform (FFT) analysis is performed on the obtained time response to calculate the scattering matrix of the S-parameters and phase frequency dependencies. Finally, the obtained results are presented and show a good agreement with those based on a hydrodynamic model.

Arbitrary waveform power controller for thermal measurements of semiconductor devices

Presented is a simple and easy-to-implement design for an arbitrary waveform power controller. The power dissipation in an active semiconductor device is controlled by virtue of its current and voltage for any waveform. By measuring the heating effect on an electronic product, an engineer can evaluate the effectiveness of its design. The controller is demonstrated practically with a MOSFET using an arbitrary waveform, and power dissipated in the device agrees well with intended dissipation.

F221004 半導体としての静電型MEMSと新機能デバイス

Theoretical consideration of electro-static MEMS taking into account physics of semiconductor is first summarized. Electric field penetration into semiconductor material of which MEMS vibrator is made is modeled in electrostatic force of MEMS actuation as a function of impurity concentration. Furthermore, fluctuation of surface carrier trapping will be considered as a noise source. Based on the theory, integration of MEMS and active semiconductor devices such as MOS FET and pn diode is reviewed as a new class of MEMS devices.

Semiconductor technologies for higher frequencies

An overview of the semiconductor active devices available for 100-GHz and 100-Gb/s applications is given, based on semiconductor properties and device requirements. The most widespread technologies are then described, and then the status of competing technologies is given in two different areas: frequency dividers, which illustrate the suitability of a technology for high-speed digital circuits, and oscillators, which illustrate their behavior in analog circuits applications. The aim of this presentation was to illustrate the variety and potential impact of these evolving technologies with consistently increasing frequency performance. While the improvement of device performance relied for a long time only on the reduction of dimensions permitted by progress in lithography, heterostructures and strain engineering are now powerful means by which to enhance performance, in both speed and power, to a level that opens a door to the 100-GHz and 100-Gb/s application arena.

Biaxially oriented CaF 2 films on amorphous substrates

Biaxially oriented CaF 2 films have been created by first using an oblique incidence vapor flux to deposit CaF 2 onto an amorphous surface to form vertically aligned nanorods which served as seeds to grow a more continuous CaF 2 capping layer under a subsequent normal incidence flux deposition. The entire film possesses a unique {1 1 1}〈1 2 1〉 biaxial texture as shown by X-ray pole figure analysis and transmission electron microscopy (TEM). This unique texture formation is a result of shadowing and surface diffusion effects. This biaxially oriented film on an amorphous substrate may be useful as a buffer layer to grow active semiconductor devices.

Experimental device for temperature investigation at high spatial and temporal resolution

Non-contact optical methods can be used for micrometric surface thermal characterization of active semiconductor devices. In this work, an experimental device based on near infra-red radiometric method is presented. This device is breadboard to analyze a thermal behaviour of electronic component in steadied and transient state. The absolute temperature distribution is measured at the micron scale. The obtained results highlight the excellent spatial and temporal resolution of the experimental measurement apparatus and its great sensitivity for detection of weak thermal emission variations.

Microwave Parametric Frequency Dividers With Conversion Gain

A novel active parametric frequency divider configuration using coupled microstrip transmission lines and two balanced pseudomorphic HEMTs (pHEMTs) is presented. The analysis of the divide-by-2 circuit presented applies the principles of subharmonic generation using a nonlinear reactance to an active semiconductor device such as a pHEMT. A 2-1-GHz active analog frequency divider is designed and fabricated, with measurements showing a 20% bandwidth, 13.5-dB conversion gain, and harmonic rejection levels of more than 22 dBc. A maximum conversion gain of 18 dB is also achieved. These higher conversion efficiencies and the ability to cascade dividers allow for higher order division ratios to be achieved with the same topology.

Micro-Raman thermometry of thermal flexure actuators

Micro-Raman spectroscopy has proven to be a valuable tool for obtaining temperature measurements in active semiconductor and MEMS devices. By using the temperature-calibrated response of the polysilicon Raman signature, we have obtained spatially resolved temperature measurements of U-shaped electro-thermal actuators. Both the peak position and the line width of the characteristic Raman peak have been used as temperature metrics. The measured thermal profiles are further compared to numerical models of the electro-thermal response of the devices as designed and fabricated. The obtained thermal profiles are in qualitative agreement with published modeled thermal profiles of similar devices and are within 15 °C of our modeled profiles. These measurements represent the first reported experimental temperature profile measurements for flexure type actuators and can be used to validate the existing models. Moreover, the comparison of line width and position-based temperatures are in good agreement, differing slightly over the flexure regions of the device.

Spatially Resolved Femtosecond Pump–Probe Spectroscopy in Broad-Area Semiconductor Lasers

We investigate the ultrafast gain dynamics in broad-area semiconductor lasers with particular emphasis on spatial and spatiotemporal effects. We present a spatially resolved femtosecond pump-probe experiment which allows us to measure the compression and recovery of the gain with 250-fs temporal and 15 /spl mu/m spatial resolution. We find a significant spatial variation of the gain recovery time across the lateral laser coordinate indicating an influence of the extended laser structure on the ultrafast carrier relaxation. Moreover, we are able to follow the spatiotemporal relaxation of the ultrafast spatiospectral gain saturation within the extended semiconductor active area. We find diffusion-like broadening of the locally suppressed gain on two distinct ultrafast timescales, within several picoseconds and several tens of picoseconds, resulting from an interplay between intraband relaxation, spatial holeburning, and light propagation. Supported by microscopic modeling, our results provide insight into the different mechanisms and timescales associated with the spatiotemporal carrier dynamics. These findings are essential for the design of laterally extended semiconductor active devices for ultrafast optical signal processing applications.

Novel zero-Voltage-transition PWM DC-DC converters

A new family of zero-voltage-switching (ZVS) pulsewidth-modulated (PWM) converters that uses a new ZVS-PWM switch cell is presented in this paper. Except for the auxiliary switch, all active and passive semiconductor devices in the ZVS-PWM converters operate at ZVS turn ON and turn OFF. The auxiliary switch operates at zero-current-switching (ZCS) turns ON and OFF. Besides operating at constant frequency, these new converters have no overvoltage across the switches and no additional current stress on the main switch in comparison to the hard-switching converter counterpart. Auxiliary components rated at very small current are used. The principle of operation, theoretical analysis, and experimental results of the new ZVS-PWM boost converter, rated 1 kW, and operating at 80 kHz, are provided in this paper to verify the performance of this new family of converters.

Efficient numerical simulation of GaAs MESFET's based on energy model and using interpolating wavelet

A fast wavelet based non-uniform grid generation method is presented for time domain simulation of active semiconductor devices. The proposed approach solves the active part model of the semiconductor device. This approach is used to solve the non-linear equations of semiconductors on the self-adaptive grids, obtained by applying wavelet. Non-uniform mesh size is implemented and controlled by the wavelet coefficients. A fine mesh is used where the unknowns are varying rapidly and a coarser mesh where the unknowns are varying slowly. The energy model is considered for active layer of transistor and its results are compared with those of the classical drift diffusion model. Performance of this method is compared with the conventional finite difference on a uniform mesh. A reduction over 80 percent of unknowns in grid together with good accuracy in simulation is obtained using this non-uniform mesh while accurate physical behaviour of the device can be predicted. This represents an ongoing effort toward a numerical technique that uses wavelet to solve physical modelling problem of semiconductor devices. Copyright © 2006 John Wiley & Sons, Ltd.

Compact ASD Topologies for Single-Phase Integrated Motor Drives with Sinusoidal Input Current

A standard configuration of an Adjustable Speed Drive (ASD) consists of two separate units: an AC motor, which runs with fixed speed when it is supplied from a constant frequency grid voltage and a frequency converter, which is used to provide the motor with variable voltage-variable frequency needed to adjust the speed ofthe motor. The integrated motor drive concept is a result of merging the two units in order to achieve the following benefits [1–3]: reducing the design and the commissioning time in complex industrial equipments, no need for a cabinet to host the frequency converter, no need for shielded cables to reduce EMI (Electro Magnetic Interference), no need for cables for the speed transducers or for other sensors for industrial process control (e.g. pressure). This solution is currently available up to 7.5 kW being not used in the medium and high power range due to a low-density integration ofthe converter caused by the large size of the passive components (electrolytic capacitors and iron chokes) and vibration ofthe converter enclosure.This paper analyzes the implementation aspects for obtaining a compact and cost effective single-phase ASD with sinusoidal input current, investigating the physical removal of power inductors from the converter enclosure in conjunction with reducing the number of semiconductor active devices. There are two ways to do that: to integrate the inductors in the unused area of the stator yoke of the motor or to use the leakage inductance of the induction motor as a boost inductor for a PFC (Power Factor Correction) stage controlled by the inverter zero-sequence voltage component. By determining how much energy is possible to store in a corner inductor, it is proven that integrating the magnetics into the stator yoke is a feasible solution. Topologies of single-phase converters that take advantage ofthe motor leakage inductance are analyzed. The installed power in silicon active devices of these topologies is compared with a standard situation, showing that this will involve higher cost. As the iron core ofthe inductors is not suitable for high frequency operation, higher core losses will occur, but outside the converter enclosure. The advantages are: the reduction of the number of active semiconductor devices, the reduction ofthe ASD size and the better integration potential.

Thermoreflectance based thermal microscope

Thermal images of active semiconductor devices are acquired and processed in real time using visible light thermoreflectance imaging with 34mK sensitivity. By using a 16×16 alternating current coupled photodiode array with synchronous frequency domain filtering a dynamic range of 123dB is achieved for 1s averaging. Thus with a stable and higher power light source, fundamentally the camera can reach 6mK sensitivity over a submicron area. The number of pixels in the image is increased to 160×160 by multiple frame image enhancement and submicron spatial resolution is achieved. The photodiode array system has a maximum 40kHz frame rate and generates a synchronous trigger for recovery of the phase signal. Amplitude and phase images of the thermoreflectance signal for 50×50 micron square active SiGe based microcoolers are presented.

Switch-mode voltage-doubler rectifier with symmetrical arrangement of capacitors for pumping action

A novel switch-mode voltage-doubler rectifier for single-phase supply is presented. It consists of diode bridge circuit and pump circuit with symmetrical arrangement of capacitors. The capacitors with energy storage/transfer capability are charged and discharged by employing the active power semiconductor devices. The rectifier can be operated in the switch mode for pumping action to pump twice the peak supply voltage into the output capacitor and for forcing the input current to follow its sinusoidal reference independent of the working conditions. The prototype tested, using two dual-IGBT power modules, has been implemented to investigate the operation with a PI controller for output voltage regulation. Experimental and simulated results are provided to verify the expected performance in both steady-state and transient conditions.

Sequential shape-and-solder-directed self-assembly of functional microsystems.

We demonstrate the fabrication of packaged microsystems that contain active semiconductor devices and passive components by using a directed self-assembly technique. The directed self-assembly is accomplished by combining geometrical shape recognition with site-specific binding involving liquid solder. Microfabricated components with matching complementary shapes, circuits, and liquid solder-coated areas were suspended in ethylene glycol and agitated by using a turbulent liquid flow to initiate the self-assembly. Microsystems were obtained by sequentially adding components of different types. Six hundred AlGaInP/GaAs light-emitting diode segments with a chip size of 200 microm were assembled onto device carriers with a yield of 100% in 2 min. Packaged light-emitting diodes formed with yields exceeding 97% as a result of two self-assembly steps in 4 min. This self-assembly procedure, based on geometrical shape recognition and subsequent binding to form mechanical and electrical connections, provides a high distinguishing power between different components and a route to nonrobotic parallel assembly of electrically functional hybrid microsystems in three dimensions.

Thermal measurements of active semiconductor micro-structures acquired through the substrate using near IR thermoreflectance

Modern, high-density integrated circuits (IC) typically use a flip chip bonding technique to increase performance on a greater number of interconnects. In doing so, the active devices of the IC are hidden under the exposed substrate, which precludes the use of typical surface thermal characterization techniques. A near infrared thermoreflectance method is described such that the temperature of active semiconductor devices can be measured through the substrate. Experimental results were obtained through a 200μm thick silicon substrate. Temperature resolution of 0.1K and spatial resolution of 5μm has been achieved. The Fabry–Perot effect, due to multiple reflections between the device and the back of the substrate, has been experimentally and theoretically analyzed. Techniques to enhance the spatial resolution will be discussed.