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A triple-mode voltage-controlled oscillator (VCO) with a wide tuning range (TR) is demonstrated experimentally by using standard 0.18- $\mu \text{m}$ CMOS process, with a wide 38.8% frequency TR from 19.93 to 29.52 GHz, a low phase noise of −122.3 dBc/Hz ± 7.8 dBc/Hz at 10-MHz offset frequencies, and an excellent figure of merit (FoM) with TR (FoMT) of −190.3 dBc/Hz. This VCO was realized by a switched-tunable inductor with a 76% inductance tunability, in addition to the MOS varactors. The VCO experiences different equivalent inductances via magnetic flux linkage modification in three different modes.

A Si-based series-shunt transmit/receive (TX/RX) switch with a high-power 1-dB compression point ( $P_{\text {1 dB}}$ ) of 29.2 dBm is demonstrated at 28 GHz for 5G communication. The proposed switch also exhibits low insertion losses of 2.86 dB/3.46 dB and reasonable isolations of 21.7 dB/19.1 dB for TX/RX modes, respectively. These excellent results were achieved by applying an LC resonator and stacked high-voltage asymmetric MOS transistors in a standard 0.18- $\mu \text{m}$ CMOS process.

An on-chip switched tunable inductor based on magnetic flux linkage modification is proposed. The magnetic flux linkage was adjusted through an auxiliary coil that was connected to a flip-flop in parallel with a MOS switch. The inductance was monotonically tuned by applying MOS gate voltages, which had a broad tuning range of 1.32–2.03 nH (42.4%) at 8 GHz. A high quality factor of 61.6 at 8 GHz was achieved because the flip-flop provided negative resistance.

Adding passive components in a conventional IGBT gate driver is a simple method to reduce transient current/voltage spikes during switching, but the extra devices and power loss make them less attractive. Alternatively, active gate drivers can improve the switching behavior, but are limited to specific devices and applications from the increased complexity of functions and feedback topology. This article reports a simple design for a general purpose gate driver methodology to reduce the peak reverse recovery current and over-voltage. The proposed topology was verified using a foundry 0.25- $\mu \text{m}$ BCD technology and experimental testing Remarkable improvements of crucial current overshoot during turn-on, voltage overshoot during turn-off, and the associated switching loss are demonstrated using novel dual-phase turn-on and turn-off gate controls.

The uneven sneak-path currents in resistive random access memory (RRAM) severely constrain the array size. To overcome this issue, we propose an innovative readout scheme that can fully offset the sneak-path currents in one-resistor (1R) RRAM array. Furthermore, the bit cell resistance $({R}_{\text {cell}}{)}$ in an RRAM array can be simply evaluated as the ratio of read voltage $({V}_{read}{)}$ to the sensed offset current $({I}_{\text {offset}}{)}$ . Even under extreme device distribution, a ${512}\times {512}$ array size is still obtained. This is the largest array among simple 1R RRAM, without using a selector device or extra transistor.

Multiple object tracking plays an important role in computer vision and video analysis. There are many problems with object tracking, such as appearance changes, distance from the camera, occlusion, moving too fast, and so on. In this paper, we combine the pre-trained pedestrian association model with a pedestrian's appearance and moving model to achieve better tracking performance. We trained a neural network base on a large dataset of pedestrian classification, together with the moving model of an object's position, velocity, and acceleration, to help us predict the trajectory more accurately. To demonstrate the performance of the proposed method, the Multiple Object Tracking (MOT) benchmark was used. Experimental results showed the proposed method achieves reasonable tracking results.

Network virtual technology can provide solutions for experimental courses. It is low-cost, function congruent advantages, and the teaching cross-regional requirements. Virtual teaching platform can be real-time interaction between teachers and students. VRML-Java synchronized platform is designed in the paper, we initially realized the online substation system, and it includes the control and protection system, monitoring system, event log and fault recorder system, same period closing system. The virtual platform solves some challenges in the prototype experiment, increases knowledge and deep understanding to students, it gets better teaching results.

We propose a novel quantum-dot sensitized solar cell (QDSSC) structure that employs a quantum dot/semiconductor silicon (QD/Si) coaxial nanorod array to replace the conventional dye/TiO2/TCO photoelectrode. We replaced the backlight input mode with top-side illumination and used a quantum dot to replace dye as the light-absorbing material. Photon-excited photoelectrons can be effectively transported to each silicon nanorod and conveyed to the counter electrode. We use two-stage metal-assisted etching (MAE) to fabricate the micro-nano hybrid structure on a silicon substrate. We then use the chemical bath deposition (CBD) method to synthesize a Sb2S3quantum dot on the surface of each silicon nanorod to form the photoelectrode for the quantum dot/semiconductor silicon coaxial nanorod array. We use a xenon lamp to simulate AM 1.5 G (1000 W/m2) sunlight. Then, we investigate the influence of different silicon nanorod arrays and CBD deposition times on the photoelectric conversion efficiency. When an NH (N-type with high resistance) silicon substrate is used, the QD/Si coaxial nanorod array synthesized by three runs of Sb2S3deposition shows the highest photoelectric conversion efficiency of 0.253%. The corresponding short-circuit current density, open-circuit voltage, and fill factor are 5.19 mA/cm2, 0.24 V, and 20.33%, respectively.

Psychoactive drug overdoses are life-threatening and require prompt and proper treatment in the emergency room to minimize morbidity and mortality. Prompt identification of the ingested psychoactive drugs is challenging, since witness recall is unreliable and patients' symptoms do not necessarily explain their loss of consciousness. Gas and liquid chromatography mass spectrometric analyses have been the traditionally employed methods to detect and identify abused substances; however, these techniques are time-consuming and labor-intensive. In this study, thermal desorption electrospray ionization mass spectrometry, an ambient mass spectrometric technique, was applied to rapidly characterize flunitrazepam, lysergic acid diethylamide, and 3,4-methylenedioxy-methamphetamine in drained gastric lavage fluid, and ketamine, cocaine, amphetamine and norketamine in whole blood samples. No pretreatment of the gastric lavage fluid specimens was required and the entire analytical process took less than 30 s per specimen. Liquid-liquid extraction, followed by centrifugation, was performed on the whole blood samples. The corresponding compounds were identified through matching the obtained mass spectrometric data with those provided by commercial databases. The limits-of-detection of the tested drugs in both drained gastric lavage fluid and whole blood samples are at sub ppm levels. This is sensitive enough for emergency medical application, since the quantities of medications ingested by overdosed abusers are much higher than the amounts that were tested.

In views of optical CDMA confidentiality, this paper proposes a signature reconfiguration scheme over the OCDMA network coder/decoders (codecs) design. By exclusively assigning to each network user a set of pseudo-orthogonal M-sequence signature codes and selecting one among them to represent each user's signature. A central node station is assumed to monitor network traffic condition and to signal transceiver coder-decoder pair to perform signature codes changing. We structure the detailed M-signature codecs design over arrayed-waveguide grating devices. We also use the successive interference cancellation (SIC) technique to enhance the system performance.

We present breakthrough performance from green and blue InGaN-based laser diodes fabricated on nonpolar/semipolar substrates. High-power, high-efficiency, and long-lifetime continuous-wave laser operation is demonstrated using these novel crystal orientations. For green wavelengths at 520 nm, we report on continuous wave single mode lasing with75 mW of output power and wall plug efficiencies over 2.3%. In the blue regime we describe single-mode lasers operating with over 23% wall plug efficiency and with output powers greater than 750 mW. These InGaN-based direct-diode lasers offer significant improvement in performance, size, weight, and cost over conventional gas and solid state lasers. Furthermore, these devices exhibit robust operation over a broad temperature range, can be directly modulated and do not contain harmful residual infrared radiation typical of second harmonic generation lasers. These characteristics are salient considerations for such optical devices in battlefield and other security applications.

Dynamic signature reconfiguration is proposed to combat with eavesdroppers to enhance confidentiality over multi-rate optical code-division multiple-access (OCDMA) networks. The code reconfiguration is achieved by exclusively assigning to each network user a set of orthogonal or pseudo-orthogonal codes and randomly selecting one among them to represent each user's signature. A central node station is assumed to monitor network traffic condition and to signal transceiver coder-decoder pair to perform signature codes changing. We illustrate the confidentiality enhancement by dynamically reconfiguring user signatures using prime-lengths M-sequence codes. When the set of signature codes increases and the eavesdropper's codes detection becomes more difficult, thus network confidentiality is significantly increased.

In this paper, a 3.24 GHz~4.56 GHz wide-band voltage-controlled oscillator (VCO) fabricated in a 0.18 ?m 1P6M CMOS process is presented. This VCO is designed with a CMOS complementary-Gm oscillator topology, features two accumulation mode MOS varactors, and body-biased pMOSs. With 1.8 V power supply, when center frequency is 3.547 GHz, the phase noise is -119.2 dBc/Hz at 1 MHz offset. The oscillation frequency can be tuned from 3.24 GHz to 4.46 GHz. The best figure of merit (FoM) is -181.18 dB, the maximum power consumption is 16.2 mW.

A novel low phase noise quadrature voltage-controlled oscillator (QVCO) with two coupled Hartley VCOs is proposed and implemented using the standard TSMC 0.18 um CMOS 1P6M process. The QVCO employs pMOS as the core to reduce the up-conversion of low-frequency device noise to RF phase noise. It uses super-harmonic coupling technique to couple two differential Hartley VCOs and four small-size coupling transistors to set the directivity of quadrature output phases. At the 1.8 V supply voltage, the output phase noise of the QVCO is -125.6 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 5.06 GHz, and the figure of merit is -188.0 dBc/Hz. At the supply voltage of 1.8 V, the total power consumption is 17.4 mW. The die area is 0.982 times 0.992 mm2.

A 5.6 GHz quadrature voltage-controlled oscillator (QVCO) designed with balanced Colpitts topology and coupled with back-gate coupling technique is presented. The use of back-gate of the core transistor as coupling terminals removes the noise contributed from the coupling transistor of conventional QVCO and reduces power consumption. The prototype is implemented using TSMC standard 0.18 mum 1P6M CMOS process technology. With 1.8 V power supply, the phase noise of the QVCO is -113 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 5.6 GHz, and tuning range is 330 MHz. The figure of merit is -174.6 dB. Power consumption is 21.6 mW.

The nonlinearity and uncertainty of the runoffs process are such that estimating or predicting required hydrologic data is often tremendous difficult. Consequently, this study applies three forecasting models to predict the ten-day streamflow resulting from rainfalls on the Kao-Ping river watershed. The three techniques employed in establishing the models include: time series, Grey system theory, and the adaptive fuzzy neural network model. Through the research it is anticipated a more appropriate hydrologic data series forecasting model for the Kao-Ping river watershed can be identified.

We demonstrate intersuband InGaN/(Al)GaN quantum well infrared photodetectors grown on a free standing non-polar m-plane GaN substrate. The devices are grown by metal organic chemical vapor deposition and exhibit TM-polarized photocurrent at peak wavelengths of 7.5 and 9.3 μm at temperature of 14 K. Based on the experimental data of intersubband and interband transition energies and 8-band k · p Schrodinger-Poisson solver calculations, we were able to estimate the conduction band offset to valence band offset discontinuity ratio (ΔEc:ΔEv) of 57:43 for In0.1Ga0.9N/GaN and 55:45, for In0.095GA0.905N/Al0.07Ga0.93N non-polar m-plane multi-quantum well structures.

Cathode electrodes on the backside of n-type nonpolar m-plane (1100) and semipolar (2021) GaN substrates after thinning were investigated. For m-plane, Al deposition after inductively coupled plasma exposure resulted in ohmic characteristics with a specific contact resistivity of 1.6 ×10-4 Ω cm2 without annealing, where the sub-micron-order pillar-like micromasking were considered to contribute to the ohmic contact. For (2021), ohmic characteristics with a specific contact resistivity of 6.9 ×10-5 Ω cm2 was confirmed with Ti/Al electrode after annealing at 500 °C. Such electrodes could improve wall-plug efficiencies of nonpolar and semipolar GaN-based optoelectronic devices.

The polarization of spontaneous emission was investigated for various indium compositions and quantum wells on m-plane oriented gallium nitride (GaN) light emitting diodes (LEDs) grown on bulk-GaN substrates. Internal light scattering and depolarization was mitigated with application of absorber materials to the LED die. The polarization ratio (ρ) was measured under electrical injection for devices with InGaN active regions emitting up to 520 nm and observed as high as 96%. Values of ρ were independent of drive current. The valence band energy separation (ΔE) was characterized using spectral measurement and temperature dependent optical analysis of valence band hole distributions.

We present the first reported continuous-wave (CW) operation of pure blue AlGaN-cladding-free (ACF) nonpolar m-plane InGaN/GaN laser diodes (LDs). CW lasing was achieved at a wavelength of 461 nm and a threshold current density of 4.1 kA/cm2 for LDs with an InGaN-based separate confinement heterostructure (SCH) waveguide design. The devices showed a 9 nm/decade blue-shift of spontaneous emission wavelength with increasing current density, a characteristic temperature of 156 K, a red-shift with increasing stage temperature of 0.05 nm/K, and an estimated thermal impedance of 60 K/W.

The growth of InGaN/AlGaN multiple quantum wells (MQWs) structures is highly effective for realizing high quality semipolar (2021) active regions for green light emitting diodes (LEDs) and laser diodes (LDs). The use of AlGaN barriers significantly improved internal quantum efficiencies and the uniformity of the emission compared to InGaN or GaN barriers. 516 nm lasing wavelength was demonstrated on semipolar (2021) GaN substrates by introducing three periods InGaN/AlGaN MQWs and the AlGaN-cladding-free optical waveguide consisting of GaN cladding and InGaN guiding layers.

Spectrally-, polarization-, and time-resolved photoluminescence (PL) experiments have been performed on 2.5 nm thick m-plane single InGaN quantum wells. It has been found that PL decay is mainly de ...

The optical characteristics of InGaN/GaN light emitting diodes (LEDs) grown on (2021) bulk GaN substrates with wavelengths 469, 487, 510, and 528 nm were investigated. From 2 to 100 mA, the peak emission wavelength for green LEDs blue-shifted by 6.2 nm. Emission spectra widths were almost independent of the injection current. These results suggest that (2021) LEDs have a smaller polarization field and smaller indium fluctuations in the quantum wells. Optical polarization ratios for the LEDs varied between 0.4 and 0.5, which are larger than reported values. A weak dependence of the polarization ratio on the indium composition was observed.

Nonpolar GaN-based light emitting diodes (LEDs) and laser diodes (LDs) show great promise. However, long wavelength emitters (λ>500 nm) have reduced performance in comparison with violet and blue nonpolar emitters. We present results of transmission electron microscopy studies of long wavelength (11¯00) m-plane GaN LED series and m-plane GaN LDs grown on high quality bulk GaN substrates. I1 basal plane stacking faults form in the high In content InxGa1−xN quantum wells (x∼0.26) for thicker wells. The I1 faults are bounded by sessile Frank–Shockley partial dislocations that likely limit the radiative efficiency of long wavelength m-plane emitters.

We have characterized and modeled the radio frequency (RF) power performance of a 0.18 µm asymmetric-lightly-doped-drain metal–oxide–semiconductor field-effect transistor (LDD MOSFET). In comparison with the conventional 0.18 µm MOSFET, this asymmetric-LDD device shows a larger power density of 0.54 W/mm, and 8 dB better adjacent channel power ratio (ACPR) linearity at 2.4 GHz from the improved twice DC breakdown voltage of 6.9 V. These significant improvements of RF power performance in the asymmetric-LDD transistor are important for the medium RF power amplifier application.

Two-dimensional optical waveguide mode simulations have been employed to investigate the optimized device structures for ridge-waveguide (Al, In, Ga) N-based green (520nm) laser diodes (LDs). The effects of thicknesses, alloy compositions, and doping densities of each epitaxially grown layers as well as ridge geometries on optical confinement factors (Γ) and waveguide absorption (α) were comprehensively surveyed. InyGa1−yN (y=0.07–0.1) guiding layers (GLs) with thickness more than 50nm were effective for realizing high Γ and low α. To minimize the absorption by the anode metal, p-cladding layer (p-CL) was required to be more than 500nm. At the same time, low index insulator such as SiO2 was preferable for the narrow ridge, where the thickness at the sidewall had to be more than 60nm. We also found that InGaN barriers layers between the quantum wells (QWs) were superior to GaN barriers to increase Γ and reduce α. Moreover, a thicker last barrier between the topmost QW and the electron blocking layer was al...

We report on the observation of rotation of spontaneous emission polarization resulting in polarization tilted with respect to transverse electric (TE) mode, in m-axis oriented semipolar (1122) (Al,In,Ga)N waveguide structures. The principle polarizations were aligned parallel and perpendicular to the c-axis, i.e., at an angle of ~30 and ~120°, respectively, with respect to TE mode. This phenomenon was attributed to birefringence of uniaxial GaN wurtzite structure. This birefringence property is an important consequence for m-axis oriented (1122) laser diode structures, since it is expected to reduce the optical gain by a factor of ~0.5–0.75.

An m-plane-GaN based blue superluminescent diode was demonstrated utilizing the asymmetric chemical properties of the ±c facets. The non-reflecting -c plane facet, intended to prevent optical feedback along the c-axis waveguide, was fabricated by KOH wet etching. KOH selectively etched the cleaved -c facet leading to the formation of hexagonal pyramids without etching the +c facet. The peak wavelength and full width at half max were 439 and 9 nm at 315 mA, respectively, with an output power of 5 mW measured out of the +c facet.

Asymmetric p-GaN/n-AlGaN-cladded InGaN-based pure blue (440–460 nm) laser diodes were fabricated based on the nonpolar m-plane GaN technology. Simulation results showed high indium content (5%–10%) InGaN wave-guiding layers mainly contributed to the optical confinement, so that n-AlGan layer can be used to control of the peak position of the optical mode to achieve high optical confinement factor and low internal loss. By using this laser structure, lasing wavelengths of 443 and 465 nm with threshold current densities 14 and 19 kA/cm2, respectively, were demonstrated without facet coating.

Nonpolar blue-green (481 nm) InGaN/GaN laser diodes (LDs) were realized by using m-plane GaN substrates with a misorientation angle of approximately 1° toward [0001] direction. The laser diode structures grown on miscut m-plane GaN substrates showed significantly smoother surface morphology compared to structures grown on nominally on-axis m-plane GaN substrates. It is contributed to lower threshold current densities, longer lasing wavelength, and higher lasing yield than those on on-axis substrates grown by the same growth condition. Material improvement based on the control of substrate misorientation is essential to achieve high performance LDs beyond the blue spectral range.

High indium content blue-green (460–520 nm) m-plane InGaN light emitting diodes (LEDs) were grown on low defect-density m-plane GaN substrates. Systematic studies were performed on packaged blue-green LED lamps by using a range of well and barrier thicknesses. Photoluminance and electroluminance peak wavelengths increased while the well width was increased from 2 to 4 nm. The highest output power was achieved for well width of 2.5 nm. The output power improved significantly with the increase in barrier thickness. Nearly blueshift-free emission was observed in all LEDs from 1–400 A/cm2 current density under pulsed operation.

We have demonstrated AlGaN-cladding-free m-plane InGaN-based blue laser diodes (LDs) using a novel structure that employs 50-nm-thick n- and p-type InxGa1-xN (x = 5–10%) as waveguiding layers. The thick, high In content InGaN waveguiding layers provided significant refractive index contrast to the GaN cladding layers, thereby eliminating the need for AlGaN cladding. Under pulsed operation, lasing was achieved at 442 nm with a threshold current density of 10 kA/cm2.

Color tuning GaN based light-emitting diodes (LEDs) both electrically and optically was investigated. Color mixing of two LED dies, one nonpolar (λp=467 nm) and one semipolar (λp=574 nm), produced white light. Electrically, the correct current was supplied to each die in order to change its correlated color temperature and Commission Internationale de l’Eclairage (CIE) chromaticity coordinates from 3287 K and (0.425, 0.413) to 7242 K and (0.303, 0.315). The optical polarization anisotropy inherent in nonpolar and semipolar wurtzite GaN allowed color tuning optically with the use of a polarizer. Several regions of the CIE diagram were explored using this method and are discussed.

Stimulated emission (SE) in the blue-green (480 nm) and green (514 nm) regime has been observed, at room temperature (RT) under optical pumping, from nonpolar m-plane (1010) and semipolar (1122) InGaN multi-quantum well (MQW) laser diode (LD) structures, respectively, grown on bulk GaN substrates. The emission intensity exhibited a clear threshold behavior with respect to the pump power. Optical anisotropy was also observed between the two perpendicular in-plane directions [1123] and [1010] for semipolar LD structures, with significantly lower pump thresholds for emission along [1123]. The SE wavelength, measured just above threshold, was blue-shifted with respect to the spontaneous emission wavelength measured just below threshold. These initial results indicate that semipolar (1122) GaN is a promising orientation for the realization of blue-green and green LDs.

In this paper, the two-dimensional hole gas (2DHG) induced in the heterojunction were investigated in detail. The density of the 2DHG was calculated at first, then, based on the semiconductor-insulator-semiconductor and superlattice critical thickness model and using the self consistent Poisson-Schrdinger calculations, the influence of the AlGaN barrier and the top GaN layer thickness on the distribution of the 2DHG were calculated when the barrier layer is fully strained and half strained. The Schottky device with this structure was fabricated and C-V measurement was made to verify the existence of the 2DHG and the validity of calculation results. Finally, the 2DHG effects on p-GaN/AlGaN/GaN Schottky photodetector were investigated. Due to the polarization and Stark effect, the spectral responses with the 10nm blue shift are observed. Under zero bias, the peak responsivity of the device is about 0.022A/W, and increases to 0.19A/W under 1V reverse bias, which approaches the theoretical limit.