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Stephen J. Pearton

Bio: Stephen J. Pearton is an academic researcher from University of Florida. The author has contributed to research in topics: Dry etching & Etching (microfabrication). The author has an hindex of 104, co-authored 1913 publications receiving 58669 citations. Previous affiliations of Stephen J. Pearton include Kyungpook National University & University of Southern California.


Papers
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TL;DR: In this paper, the photoluminescence (PL) intensity from the samples was increased by factors of 5 at 5K and ∼20 at 300K as a result of deuteration, most likely due to passivation of competing nonradiative centers.
Abstract: ZnO∕ZnCdO∕ZnO multiple quantum well samples grown on sapphire substrates by molecular beam epitaxy and annealed in situ were exposed to D2 plasmas at 150°C. The deuterium showed migration depths of ∼0.8μm for 30min plasma exposures, with accumulation of H2 in the ZnCdO wells. The photoluminescence (PL) intensity from the samples was increased by factors of 5 at 5K and ∼20 at 300K as a result of the deuteration, most likely due to passivation of competing nonradiative centers. Annealing up to 300°C led to increased migration of H2 toward the substrate but no loss of deuterium from the sample and little change in the PL intensity. The initial PL intensities were restored by annealing at ⩾400°C as H2 was evolved from the sample (∼90% loss by 500°C). By contrast, samples without in situ annealing showed a decrease in PL intensity with deuteration. This suggests that even moderate annealing temperatures lead to degradation of ZnCdO quantum wells.

11 citations

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TL;DR: In this article, a flip-chip design was used to enhance the heat dissipation of 850 nm AlGaAs/GaAs implant-apertured vertical-cavity surface-emitting lasers (VCSELs).
Abstract: The finite difference method was used to analyze the thermal characteristics of continuous wave 850 nm AlGaAs/GaAs implant-apertured vertical-cavity surface-emitting lasers (VCSELs). A novel flip-chip design was used to enhance the heat dissipation. The temperature rise in the active can be maintained below 40 °C at 4 mW output power with 10 mA current bias. By contrast, the temperature rise reaches above 60 °C without flip-chip bonding. The transient temperature during turn-on of a VCSEL was also investigated. The time needed for the device to reach the steady-state temperature was in the range of a few tenths of a millisecond, which is orders of magnitude larger than the electrical or optical switch time. Flip-chip bonding will reduce the shift of the wavelength, peak power, threshold current, and slope efficiency during VCSEL operation.

11 citations

31 Dec 1996
TL;DR: The first Symposium on III-V Nitride Materials and Processes was held in Los Angeles, California, May 6-8, 1996, and focused on recent experimental and theoretical developments and applications in the rapidly growing area of refractory 3-V nitrides.
Abstract: The First Symposium on III-V Nitride Materials and Processes was held in Los Angeles, California, May 6--8, 1996, and focused on recent experimental and theoretical developments and applications in the rapidly growing area of refractory III-V nitrides. The symposium was jointly sponsored by the Dielectric Science and Technology, Electronics and Luminescence and Display Materials Divisions of the Electrochemical Society. Subject areas included crystal growth (bulk and thin films), structure and microstructure, formation of defects, doping, optoelectronic properties and device structures. Particular attention was placed on the role of heteroepitaxy in the stabilization of the various allotropic phases (wurtzite, zincblende, sodium chloride) and the formation of native defects. Hydrogen passivation of Mg acceptors in GaN, as well as compensation, was addressed. The application of GaN, InN, AlN, ScN, etc. to optical devices (visible and UV emitters, full color displays, detectors) as well as high temperature electronics was covered in a number of presentations. Twenty two papers were processed separately for inclusion on the data base.

11 citations

Journal ArticleDOI
TL;DR: In this paper , electron beam-induced current in the temperature range from 304 to 404 K was employed to measure the minority carrier diffusion length in metal-organic chemical vapor deposition-grown p-Ga2O3 thin films with two different concentrations of majority carriers.
Abstract: Electron beam-induced current in the temperature range from 304 to 404 K was employed to measure the minority carrier diffusion length in metal–organic chemical vapor deposition-grown p-Ga2O3 thin films with two different concentrations of majority carriers. The diffusion length of electrons exhibited a decrease with increasing temperature. In addition, the cathodoluminescence emission spectrum identified optical signatures of the acceptor levels associated with the VGa−–VO++ complex. The activation energies for the diffusion length decrease and quenching of cathodoluminescence emission with increasing temperature were ascribed to the thermal de-trapping of electrons from VGa−–VO++ defect complexes.

11 citations


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TL;DR: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature.
Abstract: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

10,260 citations

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TL;DR: Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems as discussed by the authors, where the primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport.
Abstract: Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.

9,158 citations

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TL;DR: A critical review of the synthesis methods for graphene and its derivatives as well as their properties and the advantages of graphene-based composites in applications such as the Li-ion batteries, supercapacitors, fuel cells, photovoltaic devices, photocatalysis, and Raman enhancement are described.
Abstract: Graphene has attracted tremendous research interest in recent years, owing to its exceptional properties. The scaled-up and reliable production of graphene derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), offers a wide range of possibilities to synthesize graphene-based functional materials for various applications. This critical review presents and discusses the current development of graphene-based composites. After introduction of the synthesis methods for graphene and its derivatives as well as their properties, we focus on the description of various methods to synthesize graphene-based composites, especially those with functional polymers and inorganic nanostructures. Particular emphasis is placed on strategies for the optimization of composite properties. Lastly, the advantages of graphene-based composites in applications such as the Li-ion batteries, supercapacitors, fuel cells, photovoltaic devices, photocatalysis, as well as Raman enhancement are described (279 references).

3,340 citations

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TL;DR: In this article, the status of zinc oxide as a semiconductor is discussed and the role of impurities and defects in the electrical conductivity of ZnO is discussed, as well as the possible causes of unintentional n-type conductivity.
Abstract: In the past ten years we have witnessed a revival of, and subsequent rapid expansion in, the research on zinc oxide (ZnO) as a semiconductor. Being initially considered as a substrate for GaN and related alloys, the availability of high-quality large bulk single crystals, the strong luminescence demonstrated in optically pumped lasers and the prospects of gaining control over its electrical conductivity have led a large number of groups to turn their research for electronic and photonic devices to ZnO in its own right. The high electron mobility, high thermal conductivity, wide and direct band gap and large exciton binding energy make ZnO suitable for a wide range of devices, including transparent thin-film transistors, photodetectors, light-emitting diodes and laser diodes that operate in the blue and ultraviolet region of the spectrum. In spite of the recent rapid developments, controlling the electrical conductivity of ZnO has remained a major challenge. While a number of research groups have reported achieving p-type ZnO, there are still problems concerning the reproducibility of the results and the stability of the p-type conductivity. Even the cause of the commonly observed unintentional n-type conductivity in as-grown ZnO is still under debate. One approach to address these issues consists of growing high-quality single crystalline bulk and thin films in which the concentrations of impurities and intrinsic defects are controlled. In this review we discuss the status of ZnO as a semiconductor. We first discuss the growth of bulk and epitaxial films, growth conditions and their influence on the incorporation of native defects and impurities. We then present the theory of doping and native defects in ZnO based on density-functional calculations, discussing the stability and electronic structure of native point defects and impurities and their influence on the electrical conductivity and optical properties of ZnO. We pay special attention to the possible causes of the unintentional n-type conductivity, emphasize the role of impurities, critically review the current status of p-type doping and address possible routes to controlling the electrical conductivity in ZnO. Finally, we discuss band-gap engineering using MgZnO and CdZnO alloys.

3,291 citations