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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: The symmetry, reorientation kinetics, and coupling of the ground-state energy to stress have been determined for the Si As -H complex in GaAs from uniaxial stress data.
Abstract: The symmetry, reorientation kinetics, and coupling of the ground-state energy to stress have been determined for the Si As -H complex in GaAs from uniaxial stress data. The stress-induced frequency shifts of the H-stretching vibration at 2094.5 cm -1 are consistent with trigonal symmetry for the defect. The application of stress at temperatures above 85 K gives rise to a preferential alignment of the defect. The reorientation of the complex is thermally activated with an activation energy of 0.26 eV. The uniaxial stress data are consistent with the hydrogen atom being on the trigonal axis between the Si acceptor and a nearest-neighbor gallium atom

13 citations

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TL;DR: In this article, the effects of proton irradiation on the dc performance of InAlN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) with Al2O3 as the gate oxide were investigated.
Abstract: The effects of proton irradiation on the dc performance of InAlN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) with Al2O3 as the gate oxide were investigated. The InAlN/GaN MOSHEMTs were irradiated with doses ranging from 1 × 1013 to 1 × 1015 cm−2 at a fixed energy of 5 MeV. There was minimal damage induced in the two dimensional electron gas at the lowest irradiation dose with no measurable increase in sheet resistance, whereas a 9.7% increase of the sheet resistance was observed at the highest irradiation dose. By sharp contrast, all irradiation doses created more severe degradation in the Ohmic metal contacts, with increases of specific contact resistance from 54% to 114% over the range of doses investigated. These resulted in source-drain current–voltage decreases ranging from 96 to 242 mA/mm over this dose range. The trap density determined from temperature dependent drain current subthreshold swing measurements increased from 1.6 × 1013 cm−2 V−1 for the reference MOSHEM...

13 citations

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TL;DR: In this article, the InN/β-Ga2O3 type-I heterojunction has been determined to be −0.55 ± 0.11 eV and −3.35 ± 0 eV, respectively, using X-ray photoelectron spectroscopy.
Abstract: Valence and conduction band offsets of the InN/β-Ga2O3 type-I heterojunction have been determined to be −0.55 ± 0.11 eV and −3.35 ± 0.11 eV, respectively, using X-ray photoelectron spectroscopy. The InN layers were grown using atomic layer epitaxy on (−201) oriented commercial β-Ga2O3 substrates. Combining this data with published band offsets for the GaN and AlN heterojunctions to β-Ga2O3 has allowed us to predict the band offsets for the AlGaN, AlInN, and InGaN ternary alloys to β-Ga2O3. The conduction band offsets for InGaN and AlInN to β-Ga2O3 increased for high In concentration and, similarly, the valence band offsets for AlGaN and AlInN to β-Ga2O3 decreased at high Al concentration. © The Author(s) 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0281907jss]

13 citations

Journal ArticleDOI
TL;DR: In this paper, dry-etched 0.25-mu m T-shape gate pseudomorphic InGaAs channel HEMTs have been demonstrated using a Freon-12-based discharge in either electron cyclotron resonance (ECR) or reactive ion etching (RIE) systems.
Abstract: Damage-free, dry-etched 0.25- mu m T-shape gate pseudomorphic InGaAs channel HEMTs have been demonstrated. A Freon-12-based discharge was used in either electron cyclotron resonance (ECR) or reactive ion etching (RIE) systems to perform the gate recess process. Etching selectivity of more than 200 was obtained between the GaAs cap layer and the underlying AlGaAs donor layer. Self-bias voltages of -30 to -50 V were used in the etching process to minimize the damage. Pre- and post-etch clean steps were utilized to achieve uniform etch and removal of any dry-etch-related residues. Schottky diodes fabricated on n-GaAs subjected to either dry or wet etching showed no differences of barrier height, zero-bias depletion depth, and ideality factor. By using the dry etch for gate recess, very tight threshold voltage uniformity was obtained. The devices showed I-V characteristics comparable to that of devices fabricated with a wet chemical process. >

13 citations

Journal ArticleDOI
TL;DR: In this paper, the reverse saturation current in mesa Schottky diodes fabricated in the n-(Ga, Mn)N showed vertical electron mobilities of 840∼336 cm2/V
Abstract: Lateral electron mobilities in 0.2-μm-thick n-(Ga, Mn)N films were obtained from Hall measurements, producing values of 116∼102 cm2/V s in the temperature range from 298 to 373 K. These values are comparable to, but slightly lower than, electron mobilities in n-GaN of the same electron concentration. By sharp contrast, analysis of the reverse saturation current in mesa Schottky diodes fabricated in the n-(Ga, Mn)N show vertical electron mobilities of 840∼336 cm2/V s in the temperature range from 298 to 373 K. This is consistent with a reduction in electron scattering by charged dislocations for vertical transport geometries [M. Misra, A. V. Sampath, and T. D. Moustakas, Appl. Phys. Lett. 76, 1045 (2000)].

13 citations


Cited by
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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

Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
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