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Your search keyword '"Wu, Z."' showing total 196 results
Start Over Author "Wu, Z." Journal applied physics letters
196 results on '"Wu, Z."'

3. Highly polarized single mode nanobelt laser

Author

Xu, P., primary, Liu, S., additional, Tang, M., additional, Xu, X., additional, Lin, X., additional, Wu, Z., additional, ZhuGe, M., additional, Ren, Z., additional, Wang, Z., additional, Liu, X., additional, Yang, Z., additional, Raghavan, N., additional, and Yang, Q., additional

Published
2017
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4. Simultaneously improved sensitivity and response speed of β-Ga2O3 solar-blind photodetector via localized tuning of oxygen deficiency.

Author

Qian, L. X., Liu, H. Y., Zhang, W. L., Zhang, H. F., and Wu, Z. H.

Subjects
GALLIUM compounds, PHOTODETECTORS, QUANTUM efficiency, ARGON plasmas, METAL-semiconductor-metal structures, EPITAXY
Abstract

Recently, β-Ga2O3 solar-blind photodetectors (PDs) have been extensively investigated for a wide range of civil and military applications. Among them, the metal-semiconductor-metal (MSM) structure is one of the most popular candidates due to the merits of fabrication simplicity, the need for only one single-dopant active layer, easy integration with readout circuitry, high quantum efficiency, etc. However, there is generally a tradeoff between sensitivity and response speed due to the specific internal gain mechanism. In this work, MSM PDs based on the molecular beam epitaxy-grown β-Ga2O3 film were fabricated, and the metal/semiconductor (M/S) interfacial properties were tailored through the low-energy Ar-plasma pretreatment, resulting in the localized oxygen deficiency and a sharper interface. Accordingly, the PD sensitivity was dramatically improved, and the advantage of internal gain, i.e., high quantum efficiency, was preserved or became even larger. For example, the 60-W pretreated sample exhibited a high responsivity (R) of 8.41 A/W and a large specific detectivity (D*) of 1.24 × 1014 Jones, both increasing by one order of magnitude in comparison with the untreated sample. More interestingly, the response speed was unexpectedly accelerated, which is ascribed to the rapid and direct tunneling of electrons at the M/S interface as well as to the reduction in RC time constant based on the data analysis and the underlying physical principle discussion. The treatment conditions can be further optimized to counterbalance some side effects. These findings reveal an efficient technique for comprehensively improving the performance of β-Ga2O3 solar-blind PDs. [ABSTRACT FROM AUTHOR]

Published
2019
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5. Valley Zeeman splitting of monolayer MoS2 probed by low-field magnetic circular dichroism spectroscopy at room temperature.

Author

Wu, Y. J., Shen, C., Tan, Q. H., Shi, J., Liu, X. F., Wu, Z. H., Zhang, J., Tan, P. H., and Zheng, H. Z.

Subjects
MOLYBDENUM disulfide, TWO-dimensional materials (Nanotechnology), MAGNETIC circular dichroism, MAGNETIC fields, MONOMOLECULAR films, MAGNETOOPTICS
Abstract

The valley Zeeman splitting of monolayer two-dimensional (2D) materials in the magnetic field plays an important role in the valley and spin manipulations. In general, a high magnetic field (6–65 T) and low temperature (2–30 K) were two key measurement conditions to observe the resolvable valley Zeeman splitting of monolayer 2D materials in current reported experiments. In this study, we experimentally demonstrate an effective measurement scheme by employing magnetic circular dichroism (MCD) spectroscopy, which enables us to distinguish the valley Zeeman splitting under a relatively low magnetic field of 1 T at room temperature. MCD peaks related to both A and B excitonic transitions in monolayer MoS2 can be clearly observed. Based on the MCD spectra under different magnetic fields (−3 to 3 T), we obtained the valley Zeeman splitting energy and the g-factors of A and B excitons, respectively. Our results show that MCD spectroscopy is a high-sensitive magneto-optical technique to explore the valley and spin manipulation in 2D materials. [ABSTRACT FROM AUTHOR]

Published
2018
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41. Abnormal bipolar resistive switching behavior in a Pt/GaO1.3/Pt structure.

Author

Guo, D. Y., Wu, Z. P., Zhang, L. J., Yang, T., Hu, Q. R., Lei, M., Li, P. G., Li, L. H., and Tang, W. H.

Subjects
*PLATINUM, *ELECTRON transport, *METAL-semiconductor-metal structures, *GALLIUM, *SANDWICH construction (Materials), *SCHOTTKY barrier diodes
Abstract

A stable and repeatable abnormal bipolar resistive switching behavior was observed in a Pt/GaO1.3/Pt sandwich structure without an electroforming process. The low resistance state (LRS) and the high resistance state (HRS) of the device can be distinguished clearly and be switched reversibly under a train of the voltage pulses. The LRS exhibits a conduction of electron tunneling, while the HRS shows a conduction of Schottky-type. The observed phenomena are considered to be related to the migration of oxygen vacancies which changes the space charge region width of the metal/semiconductor interface and results in a different electron transport mechanism. [ABSTRACT FROM AUTHOR]

Published
2015
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42. A 1kW-class multi-stage heat-driven thermoacoustic cryocooler system operating at liquefied natural gas temperature range.

Author

Zhang, L. M., Hu, J. Y., Wu, Z. H., Luo, E. C., Xu, J. Y., and Bi, T. J.

Subjects
LIQUEFIED natural gas, PULSE tube refrigerators, HELIUM, HEAT engines, THERMOACOUSTICS
Abstract

This article introduces a multi-stage heat-driven thermoacoustic cryocooler capable of reaching cooling capacity about 1 kW at liquefied natural gas temperature range without any moving mechanical parts. The cooling system consists of an acoustically resonant double-acing traveling wave thermoacoustic heat engine and three identical pulse tube coolers. Unlike other traditional traveling wave thermoacoustic heat engines, the acoustically resonant double-acting thermoacoustic heat engine is a closed-loop configuration consists of three identical thermoacoustic conversion units. Each pulse tube cooler is bypass driven by one thermoacoustic heat engine unit. The device is acoustically completely symmetric and therefore "self-matching" for efficient traveling-wave thermoacoustic conversion. In the experiments, with 7MPa helium gas as working gas, when the heating temperature reaches 918 K, total cooling capacity of 0.88kW at 110K is obtained with a resonant frequency of about 55 Hz. When the heating temperature is 903 K, a maximum total cooling capacity at 130K of 1.20 kW is achieved, with a thermal-to-cold exergy efficiency of 8%. Compared to previously developed heat-driven thermoacoustic cryocoolers, this device has higher thermal efficiency and higher power density. It shows a good prospect of application in the field of natural gas liquefaction and recondensation. [ABSTRACT FROM AUTHOR]

Published
2015
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