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This paper explores the next stage of GaN power devices with 2-level integration of peripheral low voltage active and passive devices. The 1st level consists of protection/control/driving circuits, which potentially improves the performance and overcomes the challenges to the power devices. The 2nd level integration has high-low side on-chip integration on a 100V technology platform. The challenge of channel modulation due to substrate bias sharing is effectively eliminated by the invented new scheme. The system efficiency of DC-DC buck converter using such scheme is enhanced with lower on-state resistance and good stability.

GaN Cascode performance optimization for high efficient power applications is presented in this paper. Analytical equations of Cascode capacitance network (Ciss, Coss, Cgd) is demonstrated and the equations accuracy is verified through experimental measurement. Analysis shows that Cascode Cgd is determined by HV D-MISFETs Cds, LV Si FETs Cgd/Coss ratio, and extra zener diode capacitance. With low intrinsic capacitance HV D-MISFETs [1-2], proper LV Si FETs selection, and extra zener diode protection, optimization for Cascode switching figure-of-merit (FOM, Ron x Qgd) is well demonstrated. 8.8X lower switching figure-of-merit than commercial best-in-class Si SJ FETs [3] is achieved, double pulse test (DPT) and hard switching PFC system verification result all indicate that GaN Cascode is the promising solution and ready for next generation energy systems.

GaN smart power chip technology has been realized using a GaN-on-Si HEMT platform, featuring monolithically integrated high-voltage power devices and low-voltage peripheral devices for mixed-signal functional blocks. In particular, this brief presents the imperative analog functional block-voltage reference generator for smart power applications with wide-temperature-range stability. The circuit is capable of proper functions within a wide temperature range from room temperature up to 250°C , illustrating the unique advantage of the wide-bandgap GaN in high-temperature operation. The voltage reference generator was designed with an AlGaN/GaN HEMT and Schottky diodes, and the devices were operated in the subthreshold regime to obtain low power consumption. The voltage reference generator achieved an average drift of less than 0.5 mV/°C and can be used as a reference voltage in various biasing and sensing circuits.

We report an in situ low-damage pre-gate treatment technology in an atomic layer deposition (ALD) system prior to the ALD- Al2O3 deposition, to realize high-quality Al2O3/III-nitride (III-N) interface. The technology effectively removes the poor quality native oxide on the III-N surface while forming an ultrathin monocrystal-like nitridation interlayer (NIL) between Al2O3 and III-N surface. With the pre-gate treatment technology, high-performance Al2O3(NIL)/GaN/AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors are demonstrated, exhibiting well-behaved electrical characteristics including suppressed gate leakage current, a small subthreshold slope of ~64 mV/dec, and a small hysteresis of ~0.09 V.

In this paper, a zero-bias mixer using a lateral field-effect diode fabricated on standard GaN-on-Si AlGaN/GaN high-electron-mobility-transistor wafers is demonstrated. The diode features strong nonlinearity near zero bias, enabled by a threshold-voltage modulation using a fluorine-plasma-treatment technique. The maximum change in conductance was adjusted to ~0 V, leading to optimal conversion loss (CL) of the mixer at zero bias and eliminating the need for any dc supplies. The mixer is characterized from room temperature (RT) to 250degC . At 2.5 GHz and at RT, the CL and third-order intermodulation intercept point are 12.9 dB and 17.64 dBm, respectively. The operation of the proposed diode is modeled by a physical equivalent circuit, with the element values extracted from the measured S-parameters. The voltage-biasing dependence of the CL can be explained by the model. The high-temperature operation of the mixer shows that the proposed mixer can perform well in high-temperature and ultralow-power applications.

We present a novel and efficient motion segmentation and tracking algorithm that follows the shift and align paradigm. We introduce two statistical tests to evaluate the similarity of aligned image pixels or patches and we use them to determine the spatial extend of each segment. The one statistical test is fast and accurate when the noise is moderate and the other employs a sophisticated noise model involving the Mahalanobis distance to handle correlated noise. Direct computation of the Mahalanobis distance is prohibitively expensive so we apply the Sherman-Morrison-Woodbury identity and amortization to reduce the cost by several orders of magnitude. We tested both versions of the algorithm on a variety of image sequences (indoor and outdoor, real and synthetic, constant and varying lighting, stationary and moving camera, one of them with known ground truth) with very good results.

CMOS-compatible 100/650 V enhancement-mode FETs and 650 V depletion-mode MISFETs are fabricated on 6-inch AlGaN/GaN-on-Si wafers. They show high breakdown voltage and low specific on-resistance with good wafer uniformity. The importance of epitaxial quality is figured out in a key industrial item: high-temperature-reverse-bias-stress-induced on-state drain curent degradation. Optimization of epitaxial layers shows significant improvement of device reliability.

The finite-difference time-domain (FDTD) technique was extended to analyze the frequency response of surface acoustic wave (SAW) filters. In this method, the partial derivatives of quasi-static Maxwell's equations and the equation of motion are discretized to centered finite differences. In addition, the perfectly matched layer boundary condition was applied to reduce spurious reflections. Two structures are considered in this paper. First, the model was applied to analyze the influence of the number of electrodes on the frequency response of a SAW filter fabricated on a zinc oxide (ZnO) substrate. Then, the proposed method was further extended to analyze the frequency response of a ZnO/diamond/Si-layered SAW filter. The simulated results are in a good agreement with the existing experimental data, indicating that the FDTD method was an appropriate approach for modeling SAW devices.

In this paper, the reliable SiN x /AlGaN/GaN MISHEMTs on silicon substrate with improved trap-related characteristics have been well demonstrated. The devices with our proposed treatment method showed less deep-level traps and more Si surface donors at SiN x -AlGaN interface. The trap related device characteristics are also improved by using our optimized treatment method. The devices with proposed treatment method exhibit less current collapse and better positive bias temperature stability of threshold voltage. All the results suggest that the proposed treatment method is very effective to improve the slow-trap related device reliability.

CMOS-compatible GaN-on-silicon technology with excellent D-mode MISHFET performance is realized. A low specific contact resistance R c (0.35 Ω-mm) is achieved by Au-free process. MIS-HFET with a gate-drain distance (L GD ) of 15 μm exhibits a large breakdown voltage (BV) (980 V with grounded substrate) and a low specific on-resistance (R ON , sp ) (1.45 mΩ-cm 2 ). The importance of epitaxial quality in a key industrial qualification item: high temperature gate bias (HTGB) stress-induced voltage instability issue is figured out and a breakthrough by optimizing GaN epitaxial layer for improvement of MIS-HFET is demonstrated. A low V th shift of the optimized MIS-HFET is achieved ~ 0.14V with qualification stress condition V G of -15 V at ambient temperature of 150 oC for 128 hours.

GaN smart power chip technology has been realized on the GaN-on-Si platform, featuring monolithically integrated high-voltage power devices, and low-voltage peripheral devices for mixed-signal functional blocks. In particular, this paper presents the imperative analog functional block - the voltage reference generator for smart power applications with wide-temperature-range stability. These circuits are shown to be capable of proper functions from room temperature (RT) up to 250 °C, featuring a negative reference voltage of -2.21 V at RT, and -2.13 V at 250 °C. The optimized voltage reference generator achieved less than 0.5 mV/°C drift. It can be used to create a reference voltage for various biasing and sensing circuits.

An AlGaN/GaN HEMT-compatible lateral field-effect diode has been used for zero-bias microwave detector application. Using the versatile fluorine plasma ion treatment technique, we have been able to realize a diode that exhibits strong nonlinearity near zero bias, thus, eliminating DC supplies in microwave detector circuits. The AlGaN/GaN microwave detectors deliver high sensitivity, wide dynamic range and high temperature operating capability. The maximum zero-bias curvature coefficient (?) measured are 11.6 V -1 and 3.2 V -1 at 50°C and 250°C, respectively, yielding a directly-measured sensitivity (sv) of 1027 mV/mW at 50°C and 466 mV/mW at 250°C. The peak conjugately-matched sensitivity (sv,opt) is projected to be 9030 mV/mW at 2 GHz at 50°C. At room temperature, the wide dynamic range of 53 and 54 dB at 2 and 5 GHz are observed, respectively, both of which are the highest values reported so far.

With an in situ low-damage NH3-Ar-N2 plasma pre-gate treatment, a high-quality Al2O3/GaN-cap interface has been obtained in the Al2O3/GaN/AlGaN/GaN MIS-structures. Frequency- and temperature-dependent C-V characterization techniques were developed to map the interface trap density (Dit) at the dielectric/III-nitride interface, whereby a low Dit of ~1012-1013 cm-2eV-1 in the Al2O3/GaN/AlGaN/GaN MIS-structures was extracted. The mechanism for the high-quality interface was validated to be effective removal of native oxide and the subsequent formation of a monocrystal-like nitridation inter-layer on the GaN surface. Both Dit mapping and the pre-gate treatment techniques are of significance for the improvement of III-nitride MIS-HEMTs.

We demonstrate a single-chip switch-mode boost converter that features a monolithically integrated lateral field-effect rectifier (L-FER) and a normally off transistor switch. The circuit was fabricated on a standard AlGaN/GaN HEMT epitaxial wafer grown with GaN-on-Si technology. The fabricated rectifier with a drift length of 15 mum exhibits a breakdown voltage of 470 V, a turn-on voltage of 0.58 V, and a specific on-resistance of 2.04 mOmegaldrcm2. The L-FER exhibits no reverse recovery current associated with the turn-off transient because of its unipolar nature. A prototype of GaN-based boost converter that includes monolithically integrated rectifiers and transistors is demonstrated using conventional GaN-on-Si wafers for the first time to prove the feasibility of the GaN-based power IC technology.

A high performance 22/20nm CMOS bulk FinFET achieves the best in-class N/P I on values of 1200/1100 µA/µm for I off =100nA/µm at 1V. Excellent device electrostatic control is demonstrated for gate length (L gate ) down to 20nm. Dual-Epitaxy and multiple stressors are essential to boost the device performance. Dual workfunction (WF) with an advanced High-K/Metal gate (HK/MG) stack is deployed in an integration-friendly CMOS process flow. This dual-WF approach provides excellent V th roll-off immunity in the short-channel regime that allows properly positioning the long-channel device V th . Enhanced 193nm immersion lithography has enabled the stringent requirements of the 22/20nm ground rules. Reliability of our advanced HK/MG stack is promising. Excellent SRAM static noise margin at 0.45V is reported.

A zero-bias microwave detector using AlGaN/GaN-based lateral field-effect diode is demonstrated. The diode is compatible with AlGaN/GaN HEMT in fabrication process. Taking advantage of threshold-voltage modulation of fluorine plasma treatment technique, the diode features low turn-on voltage and strong nonlinearity at zero bias thus eliminating DC supplies for the application of zero-bias microwave detection. The diode exhibits good sensitivity from room temperature to 250 °C. The peak on-wafer measured sensitivity (β v ) of 1027 mV/mW is achieved at 5 GHz at 50 °C. The maximum conjugately-matched sensitivity (β v,opt ) of 9030 mV/mW is obtained at 2 GHz at 50 °C and decreases to 1227 mV/mW at 250 °C. At room temperature, the dynamic range as high as 53 and 54 dB at 2 and 5 GHz is observed, respectively, which are the highest values reported so far.

GaN smart power chip technology has been realized using GaN-on-Si HEMT platform, featuring monolithically integrated high-voltage power devices and low-voltage peripheral devices for mixed-signal functional blocks. Two imperative functional blocks for smart power applications with wide-temperature-range stability are demonstrated. The first one is a voltage reference generator, and the second one is a temperature-compensated comparator. These circuits are capable of proper functions within a wide temperature range from room temperature up to 250 °C, illustrating the unique advantage of the wide-bandgap GaN. The voltage reference generator was designed with an AlGaN/GaN HEMT and Schottky diodes, and the devices were operated in the subthreshold regime to obtain low power consumption. The voltage reference generator achieved an average drift of less than 70 ppm/°C and can be used as a reference voltage in various biasing and sensing circuits. The temperature-dependent performance of a conventional comparator is characterized and a new temperature-compensated comparator circuit is proposed. The positive limiting level of the temperature-compensated comparator is less than 450 ppm/°C drift compared to 1350 ppm/°C in the conventional comparator.

A HEMT-compatible power lateral field effect rectifier (L-FER) is reported and fabricated using the CF4 plasma treatment on a GaN-on-Si wafer. The power rectifier features a Schottky-gate-controlled two-dimensional electron gas (2DEG) channel between the cathode and anode. By tying up the Schottky gate and anode together, the forward turn-on voltage (VF, ON) of the rectifier is determined by the threshold voltage of the channel instead of the Schottky barrier. The L-FER with a drift length of 15 μm features a VF, ON of 0.78 V at a current density of 100 A/cm2. This device also exhibits a reverse breakdown voltage (BV) of 460 V at a current level of 1mA/mm and a specific on-resistance (RON, sp) of 2.3 mΩ·cm2, yielding a figure-of-merit (BV2/RON, sp) of 92 MW/cm2. The high temperature characteristics of the L-FER are also investigated. The measurement results show a robust high temperature operation up to 250 °C. The excellent device performances, together with the lateral device structure and process compatibility with AlGaN/GaN HEMT, provide a low-cost solution for GaN power integrated circuits. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A lateral field-effect rectifier (L-FER) that can be fabricated with normally-off transistor on the same AlGaN/GaN HEMT with the same fabrication process has been demonstrated. The L-FER exhibits low turn-on voltage, low specific on-resistance and high reverse breakdown. A prototype of switch-mode dc-dc boost converter that features monolithically integrated L-FER and normally-off HEMT is demonstrated for the first time using industry-standard GaNon-Si epitaxial wafers to prove the feasibility of GaN power integrated technology.

The lateral field effect rectifier (L-FER) on AlGaN/GaN heterostructure on silicon substrate compatible with the HEMT process has been characterized for high temperature operation (up to 250 degC). The proposed rectifier takes advantage of adjusting the forward-on voltage to a slightly positive value by fluorine plasma treatment. The temperature dependences of the forward-on voltage and the on-resistance of the rectifiers with different drift lengths were measured. The knee voltage of the rectifier exhibits very little temperature dependence as the temperature raised to 250 degC. These results indicate that L-FER is promising for operation over a wide range of ambient temperatures.

In conclusion, an AlGaN/GaN HEMT-compatible lateral field-effect rectifier is demonstrated by utilizing the threshold-voltage controlling capability of the fluorine plasma treatment technique. The rectifier features low on-resistance, low turn-on voltage, high temperature operation and high reverse breakdown voltage. The rectifier is expected to exhibit fast reverse recovery time because of its unipolar nature. In addition, the rectifiers are fabricated with the same process as the normally-off AlGaN/GaN HEMTs, indicating a robust low-cost approach of realizing GaN-based power integrated circuits.

Surface acoustic wave (SAW) devices using two-dimensional electron gas (2DEG) as interdigital transducers (IDTs) on AlGaN/GaN heterostructure has been demonstrated using a planar isolation technique based on the fluoride-based (CF4) plasma treatment technique. The RF characteristics of the SAW filters with planar 2DEG IDTs are compared with SAW devices that are made of metal IDTs or hybrid metal/2DEG IDTs.

Surface acoustic wave (SAW) filters using two-dimensional electron gas (2DEG) as interdigital transducers (IDT) on AlGaN/GaN heterostructure has been demonstrated for the first time using a fluoride-based (CF4) plasma treatment technique. The CF4 plasma treatment is used to pattern 2DEG IDT on a planar surface without removing the top AlGaN layer. The RF characteristics of the SAW filters with planar 2DEG IDTs are compared with metal IDT SAW filters. It is shown that the massloading effects and the triple-transit-interference (TTI) are suppressed in the 2DEG IDT SAW devices owing to the removal of the metal IDTs. It is capable of reducing not only the passband ripple, but also the size of devices because 2DEG IDTs can be placed closer. In addition, the detection part of the SAW sensor can be performed on the top of the planar 2DEG IDTs rather than in the SAW propagation path. This novel SAW device can be integrated with high-electron mobility transistors (HEMTs) on AlGaN/GaN heterostructure to deliver a viable approach for single chip GaN wireless sensors.

The finite-difference time-domain (FDTD) method is extended to analyze layered surface acoustic wave (SAW) filters. In this method, the partial derivatives of quasi-static Maxwell's equations and the equation of motion are discretized to centered finite-differences. In addition, the perfectly matched layer (PML) boundary condition is applied to reduce the spurious reflections. The proposed method is used to analyze a ZnO/Diamond/Si layered SAW filter with electrode massloading. The simulated results are in a good agreement with the existing experimental data, indicating that the FDTD method is an appropriate approach for modeling SAW devices.

The finite-difference time-domain (FDTD) method is extended to analyze surface acoustic wave (SAW) filter fabricated on an anisotropic substrate. In this method, the partial derivatives of quasi-static Maxwell's equations and equation of motion are discretized to centered finite-differences. The spatial layout of the field components of this study differs from that of the isotropic case. The current two-dimensional spatial layout needs two components on particle velocity and electrical field nodes, three components on a stress node, in contrast to the isotropic case which requires one component on a particle velocity node, and one or two components on a stress node. Furthermore, the perfectly matched layer (PML) boundary condition is applied to reduce the spurious reflections. The proposed method is used to analyze the frequency response of a SAW filter fabricated on a Y-Z lithium tantalate (LiTaO3) substrate.

We demonstrate a new planar fabrication technology for integrating surface acoustic wave (SAW) filters with high-electron mobility transistors (HEMTs) on AlGaN/GaN heterostructures using fluoride-based (CF4) plasma treatment techniques. The CF4 plasma treatment has been shown capable of effectively depleting the two-dimensional electron gas (2DEG) without removing the top AlGaN layer. It is not only able to achieve the same level of active device isolation, but also able to permit the acousto-electric transductions in the interdigital transducers (IDTs) of the SAW filters. The RF characteristics of the planar SAW filter was similar to those of SAW filters directly fabricated on GaN layer exposed by using the mesa etching. Compared to the SAW device without HEMT, the integrated SAW/HEMT exhibited an insertion loss that was 5.129 dB lower because of the amplification by the output HEMT

We present a new algorithm that does motion segmentation by tracking small textured patches and then clustering them using EM. A small patch has the advantage that its motion is well modeled by uniform flow and runs a lower risk of boundary inclusion. Inherently, a small patch has less data so it is more susceptible to noise and it is not well suited to fit locally higher order flow models. To overcome these difficulties, we introduce a motion coherence detector to select only the best features and an efficient statistical technique to compute segment-wise affine flow from the EM clustering parameters. We incorporate a residual noise model without any statistical independence assumption and an efficient χ^2 test for the noise model to obtain dense segmentation. Computational efficiency is striven for within a rigorous mathematical framework. Experiments with real image sequences show good segments under a variety of conditions.

Man yc lustering problems in Computer Vision group data points that are the result of statistical estimation and these data points can have a great amount of uncertainty . Motion segmentation by clustering of optical flo wi ss uch an example because very often optical flo wc annot be estimated without significant uncertainty .W ep resent a EM based clustering algorithm for incomplete data and we apply it to the problem of motion segmentation. The input to the algorithm are the velocity likelihoods and the number of clusters. The algorithm is mathematically very elegant because it does not impose any constraints on the velocity likelihood thus multi-modal likelihood is modeled without difficulty .C oupled with a sophisticated correlated image noise model, the algorithm can handle substantial deviations from the intensity constanc ya ssumption. Experiments with real image sequences sho we xcellent results. 1. Intr oduction The process of grouping pixels having similar motion characteristics is called motion segmentation .Ap opular approach for describing motion similarity within a se gment/layer [12] is by their optical flow. T he computation of optical flo wa tap ixel is an under-constrained problem and the classical solutions [2] almost exclusively use constraints from neighboring pixels by assuming one of the several smoothness constraints which usually do not hold on object boundaries. Motion segmentation based on optical flo wi st hus a chicken and egg problem: In order to compute flo wa ccurately ,w en eed to kno wm otion boundaries but locating the motion boundaries amounts to doing segmentation which requires flo wa si nput. Our approach subscribes to the paradigm [4] that does motion segmentation without computing the full optical flo wf irst.

This paper presents the dc and dynamic characterizations of a GaN-based voltage comparator, fabricated with monolithic integration of enhancement-mode (E-mode) and depletion-mode (D-mode) AlGaN/GaN high electron mobility transistors (HEMTs). The comparator features high gain (>31 dB) and wide bandwidth (>4 MHz), and small propagation delay time (

A high electron mobility transistor (HEMT)-compatible power lateral field-effect rectifier (L-FER) with low turn-on voltage is demonstrated using the same fabrication process as that for normally off AlGaN∕GaN HEMT, providing a low-cost solution for GaN power integrated circuits. The power rectifier features a Schottky-gate-controlled two-dimensional electron gas channel between the cathode and anode. By tying up the Schottky gate and anode together, the forward turn-on voltage of the rectifier is determined by the threshold voltage of the channel instead of the Schottky barrier. The L-FER with a drift length of 10μm features a forward turn-on voltage of 0.63V at a current density of 100A∕cm2. This device also exhibits a reverse breakdown voltage (BV) of 390V at a current level of 1mA∕mm and a specific on resistance (RON,sp) of 1.4mΩcm2, yielding a figure of merit (BV2∕RON,sp) of 108MW∕cm2. The excellent device performance, coupled with the lateral device structure and process compatibility with AlGaN∕GaN...

Surface acoustic wave (SAW) devices using two-dimensional electron gas (2DEG) as interdigital transducers (IDTs) on AlGaN∕GaN heterostructure has been demonstrated using a planar isolation technique based on the fluoride-based (CF4) plasma treatment technique. The rf characteristics of the SAW filters with planar 2DEG IDTs are compared with SAW devices that are made of metal IDTs or hybrid metal/2DEG IDTs.