The Experts below are selected from a list of 57318 Experts worldwide ranked by ideXlab platform
Dim-lee Kwong - One of the best experts on this subject based on the ideXlab platform.
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high performance waveguided ge on soi metal semiconductor metal photodetectors with novel silicon carbon si c schottky barrier Enhancement Layer
IEEE Photonics Technology Letters, 2008Co-Authors: Kah-wee Ang, Shiyang Zhu, Dim-lee KwongAbstract:We report the demonstration of waveguided germanium-on-silicon-on-insulator metal-semiconductor-metal (MSM) photodetectors with novel silicon-carbon (Si:C) Schottky barrier Enhancement Layer. Significant suppression of dark current (/dark) by ~4 orders of magnitude was achieved over a conventional MSM photodetector due to an enhanced hole Schottky barrier height of 0.52 eV. At an applied bias VA of 1.0 V a -3-dB bandwidth of ~12 GHz at an incident wavelength of 1550 nm was demonstrated. Optical measurements performed at photon wavelengths lambda of 1520-1570 nm reveal a uniform spectral response and quantum efficiency of ~760 mA/W and ~60%, respectively, demonstrating an effective photodetection for the entire C-band spectrum range.
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High-Performance Waveguided Ge-on-SOI Metal–Semiconductor–Metal Photodetectors With Novel Silicon–Carbon (Si : C) Schottky Barrier Enhancement Layer
IEEE Photonics Technology Letters, 2008Co-Authors: Kah-wee Ang, Shiyang Zhu, Dim-lee KwongAbstract:We report the demonstration of waveguided germanium-on-silicon-on-insulator metal-semiconductor-metal (MSM) photodetectors with novel silicon-carbon (Si:C) Schottky barrier Enhancement Layer. Significant suppression of dark current (/dark) by ~4 orders of magnitude was achieved over a conventional MSM photodetector due to an enhanced hole Schottky barrier height of 0.52 eV. At an applied bias VA of 1.0 V a -3-dB bandwidth of ~12 GHz at an incident wavelength of 1550 nm was demonstrated. Optical measurements performed at photon wavelengths lambda of 1520-1570 nm reveal a uniform spectral response and quantum efficiency of ~760 mA/W and ~60%, respectively, demonstrating an effective photodetection for the entire C-band spectrum range.
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Novel Silicon-Carbon (Si:C) Schottky Barrier Enhancement Layer for Dark-Current Suppression in Ge-on-SOI MSM Photodetectors
IEEE Electron Device Letters, 2008Co-Authors: Kah-wee Ang, Shiyang Zhu, Jian Wang, Khai-tze Chua, Dim-lee KwongAbstract:This letter reports the first demonstration of an evanescent coupled germanium-on-silicon-on-insulator (Ge-on-SOI) metal-semiconductor-metal (MSM) photodetector with a novel silicon-carbon (Si:C) Schottky barrier Enhancement Layer. Through the insertion of a Si:C barrier Layer between the metal/Ge interface, the hole Schottky barrier height phibh can effectively be enhanced to ~0.52 eV above the valence band edge. As a result, significant dark-current IDark suppression by more than four orders of magnitude was demonstrated, leading to an impressive IDark of ~11.5 nA for an applied bias VA of 1.0 V. Optical measurements performed at a photon wavelength of 1550 nm revealed the achievement of good internal responsivity and quantum efficiency of ~530 mA/W and 42.4%, respectively, making such a high-performance Ge-on-SOI MSM photodetector a promising option for optical communication applications.
Kah-wee Ang - One of the best experts on this subject based on the ideXlab platform.
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high performance waveguided ge on soi metal semiconductor metal photodetectors with novel silicon carbon si c schottky barrier Enhancement Layer
IEEE Photonics Technology Letters, 2008Co-Authors: Kah-wee Ang, Shiyang Zhu, Dim-lee KwongAbstract:We report the demonstration of waveguided germanium-on-silicon-on-insulator metal-semiconductor-metal (MSM) photodetectors with novel silicon-carbon (Si:C) Schottky barrier Enhancement Layer. Significant suppression of dark current (/dark) by ~4 orders of magnitude was achieved over a conventional MSM photodetector due to an enhanced hole Schottky barrier height of 0.52 eV. At an applied bias VA of 1.0 V a -3-dB bandwidth of ~12 GHz at an incident wavelength of 1550 nm was demonstrated. Optical measurements performed at photon wavelengths lambda of 1520-1570 nm reveal a uniform spectral response and quantum efficiency of ~760 mA/W and ~60%, respectively, demonstrating an effective photodetection for the entire C-band spectrum range.
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High-Performance Waveguided Ge-on-SOI Metal–Semiconductor–Metal Photodetectors With Novel Silicon–Carbon (Si : C) Schottky Barrier Enhancement Layer
IEEE Photonics Technology Letters, 2008Co-Authors: Kah-wee Ang, Shiyang Zhu, Dim-lee KwongAbstract:We report the demonstration of waveguided germanium-on-silicon-on-insulator metal-semiconductor-metal (MSM) photodetectors with novel silicon-carbon (Si:C) Schottky barrier Enhancement Layer. Significant suppression of dark current (/dark) by ~4 orders of magnitude was achieved over a conventional MSM photodetector due to an enhanced hole Schottky barrier height of 0.52 eV. At an applied bias VA of 1.0 V a -3-dB bandwidth of ~12 GHz at an incident wavelength of 1550 nm was demonstrated. Optical measurements performed at photon wavelengths lambda of 1520-1570 nm reveal a uniform spectral response and quantum efficiency of ~760 mA/W and ~60%, respectively, demonstrating an effective photodetection for the entire C-band spectrum range.
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Novel Silicon-Carbon (Si:C) Schottky Barrier Enhancement Layer for Dark-Current Suppression in Ge-on-SOI MSM Photodetectors
IEEE Electron Device Letters, 2008Co-Authors: Kah-wee Ang, Shiyang Zhu, Jian Wang, Khai-tze Chua, Dim-lee KwongAbstract:This letter reports the first demonstration of an evanescent coupled germanium-on-silicon-on-insulator (Ge-on-SOI) metal-semiconductor-metal (MSM) photodetector with a novel silicon-carbon (Si:C) Schottky barrier Enhancement Layer. Through the insertion of a Si:C barrier Layer between the metal/Ge interface, the hole Schottky barrier height phibh can effectively be enhanced to ~0.52 eV above the valence band edge. As a result, significant dark-current IDark suppression by more than four orders of magnitude was demonstrated, leading to an impressive IDark of ~11.5 nA for an applied bias VA of 1.0 V. Optical measurements performed at a photon wavelength of 1550 nm revealed the achievement of good internal responsivity and quantum efficiency of ~530 mA/W and 42.4%, respectively, making such a high-performance Ge-on-SOI MSM photodetector a promising option for optical communication applications.
Shiyang Zhu - One of the best experts on this subject based on the ideXlab platform.
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high performance waveguided ge on soi metal semiconductor metal photodetectors with novel silicon carbon si c schottky barrier Enhancement Layer
IEEE Photonics Technology Letters, 2008Co-Authors: Kah-wee Ang, Shiyang Zhu, Dim-lee KwongAbstract:We report the demonstration of waveguided germanium-on-silicon-on-insulator metal-semiconductor-metal (MSM) photodetectors with novel silicon-carbon (Si:C) Schottky barrier Enhancement Layer. Significant suppression of dark current (/dark) by ~4 orders of magnitude was achieved over a conventional MSM photodetector due to an enhanced hole Schottky barrier height of 0.52 eV. At an applied bias VA of 1.0 V a -3-dB bandwidth of ~12 GHz at an incident wavelength of 1550 nm was demonstrated. Optical measurements performed at photon wavelengths lambda of 1520-1570 nm reveal a uniform spectral response and quantum efficiency of ~760 mA/W and ~60%, respectively, demonstrating an effective photodetection for the entire C-band spectrum range.
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High-Performance Waveguided Ge-on-SOI Metal–Semiconductor–Metal Photodetectors With Novel Silicon–Carbon (Si : C) Schottky Barrier Enhancement Layer
IEEE Photonics Technology Letters, 2008Co-Authors: Kah-wee Ang, Shiyang Zhu, Dim-lee KwongAbstract:We report the demonstration of waveguided germanium-on-silicon-on-insulator metal-semiconductor-metal (MSM) photodetectors with novel silicon-carbon (Si:C) Schottky barrier Enhancement Layer. Significant suppression of dark current (/dark) by ~4 orders of magnitude was achieved over a conventional MSM photodetector due to an enhanced hole Schottky barrier height of 0.52 eV. At an applied bias VA of 1.0 V a -3-dB bandwidth of ~12 GHz at an incident wavelength of 1550 nm was demonstrated. Optical measurements performed at photon wavelengths lambda of 1520-1570 nm reveal a uniform spectral response and quantum efficiency of ~760 mA/W and ~60%, respectively, demonstrating an effective photodetection for the entire C-band spectrum range.
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Novel Silicon-Carbon (Si:C) Schottky Barrier Enhancement Layer for Dark-Current Suppression in Ge-on-SOI MSM Photodetectors
IEEE Electron Device Letters, 2008Co-Authors: Kah-wee Ang, Shiyang Zhu, Jian Wang, Khai-tze Chua, Dim-lee KwongAbstract:This letter reports the first demonstration of an evanescent coupled germanium-on-silicon-on-insulator (Ge-on-SOI) metal-semiconductor-metal (MSM) photodetector with a novel silicon-carbon (Si:C) Schottky barrier Enhancement Layer. Through the insertion of a Si:C barrier Layer between the metal/Ge interface, the hole Schottky barrier height phibh can effectively be enhanced to ~0.52 eV above the valence band edge. As a result, significant dark-current IDark suppression by more than four orders of magnitude was demonstrated, leading to an impressive IDark of ~11.5 nA for an applied bias VA of 1.0 V. Optical measurements performed at a photon wavelength of 1550 nm revealed the achievement of good internal responsivity and quantum efficiency of ~530 mA/W and 42.4%, respectively, making such a high-performance Ge-on-SOI MSM photodetector a promising option for optical communication applications.
Kenneth Rose - One of the best experts on this subject based on the ideXlab platform.
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ICASSP - On scalable coding of hidden Markov sources
2016 IEEE International Conference on Acoustics Speech and Signal Processing (ICASSP), 2016Co-Authors: Mehdi Salehifar, Tejaswi Nanjundaswamy, Kenneth RoseAbstract:While several real world signals, such as speech, image and sensor network data, are modeled as hidden Markov sources (HMS) for recognition and analysis applications, their typical compression exploits temporal correlations by modeling them as simple (non-hidden) Markov sources. However, the inherent hidden Markov nature of these sources implies that an observed sample depends, in fact, on all past observations, thus rendering simple Markov modeling suboptimal. Motivated by this realization, previous work from our lab derived a technique to optimally quantize and compress HMS. In this paper we build on, and considerably extend, these results to the problem of scalable coding of HMS. At the base Layer, as proposed earlier, the approach tracks an estimate of the state probability distribution and adapts the encoder structure accordingly. At the Enhancement Layer, the state probability distribution is refined using available information from past Enhancement Layer reconstructed samples, and this refined estimate is further combined with quantization information from the base Layer, to effectively characterize the probability density of the current sample conditioned on all available information. We update code parameters on the fly, at each observation, at both the encoder and the decoder and at both Layers. Experimental results validate the superiority of the proposed approach with considerable gains over standard predictive coding employing a simple Markov model.
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An Estimation-Theoretic Framework for Spatially Scalable Video Coding
IEEE transactions on image processing : a publication of the IEEE Signal Processing Society, 2014Co-Authors: Jingning Han, Vinay Melkote, Kenneth RoseAbstract:This paper focuses on prediction optimality in spatially scalable video coding. It draws inspiration from an estimation-theoretic prediction framework for quality (SNR) scalability earlier developed by our group, which achieved optimality by fully accounting for relevant information from the current base Layer (e.g., quantization intervals) and the Enhancement Layer, to efficiently calculate the conditional expectation that forms the optimal predictor. It was central to that approach that all Layers reconstruct approximations to the same original transform coefficient. In spatial scalability, however, the Layers encode different resolution versions of the signal. To approach optimality in Enhancement Layer prediction, this paper departs from existing spatially scalable codecs that employ pixel domain resampling to perform interLayer prediction. Instead, it incorporates a transform domain resampling technique that ensures that the base Layer quantization intervals are accessible and usable at the Enhancement Layer despite their differing signal resolutions, which in conjunction with prior Enhancement Layer information, enable optimal prediction. A delayed prediction approach that complements this framework for spatial scalable video coding is then provided to further exploit future base Layer frames for additional Enhancement Layer coding performance gains. Finally, a low-complexity variant of the proposed estimation-theoretic prediction approach is also devised, which approximates the conditional expectation by switching between three predictors depending on a simple condition involving information from both Layers, and which retains significant performance gains. Simulations provide experimental evidence that the proposed approaches substantially outperform the standard scalable video codec and other leading competitors.
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PV - An estimation-theoretic framework for spatially scalable video coding with delayed prediction
2012 19th International Packet Video Workshop (PV), 2012Co-Authors: Jingning Han, Vinay Melkote, Kenneth RoseAbstract:A novel estimation-theoretic (ET) approach is developed for optimal Enhancement Layer prediction, in spatially scalable video coding (SVC), which incorporates motion compensation at the Enhancement Layer, with both current and future information from the base Layer. It is inspired by the early ET framework (originated in our group) for quality (SNR) scalability, which achieved optimal Enhancement Layer prediction by fully accounting for information from the current base Layer (e.g., the quantization intervals) and the Enhancement Layer, to efficiently calculate the conditional expectation that forms the optimal predictor. Central to that approach was the fact that all Layers reconstruct approximations to the same original transform coefficient. This, however, is not the case in spatial scalability, where the Layers encode different resolution versions of the signal. To approach optimal Enhancement Layer prediction, the current work departs from existing spatial SVC schemes that employ pixel-domain resampling and causal prediction. Instead, it integrates a transform domain resampling technique that makes the base Layer quantization intervals and reconstructions accessible to and usable at the Enhancement Layer. The approach is extended for an SVC framework that allows delay in Enhancement Layer coding relative to the base Layer, and achieves optimal delayed prediction, in conjunction with spatial SVC. Simulations provide experimental evidence that the overall proposed approach substantially outperforms existing spatially scalable coders.
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ICASSP - A conditional Enhancement-Layer quantizer for the scalable MPEG advanced Audio Coder
IEEE International Conference on Acoustics Speech and Signal Processing, 2002Co-Authors: Aggarwal Ashish D, Kenneth RoseAbstract:We propose an efficient Enhancement-Layer quantizer which considerably improves the bit rate scalability of the multi-Layer Advanced Audio Coder (AAC). The scheme exploits the statistical dependence of the Enhancement-Layer signal on the base-Layer quantization parameters. It fundamentally extends the prior work on compander domain scalability, which was shown to be asymptotically optimal for entropy coded uniform scalar quantizer, to systems with non-uniform base-Layer quantization. We show that an Enhancement-Layer quantization which is conditional on the base-Layer information can be efficiently implemented within the AAC framework to achieve major performance gains. Moreover, in the important case that the source is well modeled as Laplacian, we show that the optimal conditional quantizer is implementable by only two distinct switchable quantizers depending on whether or not the base-Layer quantizer employed the “zero dead-zone.” Hence, major savings in bit rate are recouped at virtually no additional computational cost. For example, the proposed four Layer scalable coder consisting of 16kbps Layers achieves performance close to a 60kbps non-scalable coder on the standard test database of 44.1kHz audio.
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ICASSP (5) - Efficient scalable coding of stereophonic audio by conditional quantization and estimation-theoretic prediction
2003 IEEE International Conference on Acoustics Speech and Signal Processing 2003. Proceedings. (ICASSP '03)., 1Co-Authors: Ashish Aggarwal, Sang-uk Ryu, Kenneth RoseAbstract:The standard scalable coding of stereophonic audio suffers from significant performance loss because of (1) poor prediction gain at the Enhancement-Layer and (2) direct requantization of the reconstruction error, which is suboptimal for the noise-mask ratio (NMR) criterion. To mitigate such performance loss, this paper proposes an integrated approach which employs two complementary techniques, namely, the estimation theoretic (ET) predictor and the conditional Enhancement-Layer quantizer (CELQ). The ET predictor has been shown to combine information from various sources for efficient Enhancement-Layer prediction, while CELQ efficiently handles scalable quantization to minimize NMR. We demonstrate that the proposed combined approach can achieve major performance gains in terms of bit rate reduction and reconstruction quality Enhancement. For example, the proposed 2/spl times/16 kbit/s two Layer coder achieves considerably improved reconstruction quality compared to that of the conventional 4/spl times/16 kbit/s four Layer coder, despite expending only 50% of the standard scalable coder bit rate.
Jian Wang - One of the best experts on this subject based on the ideXlab platform.
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Novel Silicon-Carbon (Si:C) Schottky Barrier Enhancement Layer for Dark-Current Suppression in Ge-on-SOI MSM Photodetectors
IEEE Electron Device Letters, 2008Co-Authors: Kah-wee Ang, Shiyang Zhu, Jian Wang, Khai-tze Chua, Dim-lee KwongAbstract:This letter reports the first demonstration of an evanescent coupled germanium-on-silicon-on-insulator (Ge-on-SOI) metal-semiconductor-metal (MSM) photodetector with a novel silicon-carbon (Si:C) Schottky barrier Enhancement Layer. Through the insertion of a Si:C barrier Layer between the metal/Ge interface, the hole Schottky barrier height phibh can effectively be enhanced to ~0.52 eV above the valence band edge. As a result, significant dark-current IDark suppression by more than four orders of magnitude was demonstrated, leading to an impressive IDark of ~11.5 nA for an applied bias VA of 1.0 V. Optical measurements performed at a photon wavelength of 1550 nm revealed the achievement of good internal responsivity and quantum efficiency of ~530 mA/W and 42.4%, respectively, making such a high-performance Ge-on-SOI MSM photodetector a promising option for optical communication applications.