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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, an interface trap density of 5 X 10 1 1 1 eV - 1 cm - 2 was obtained with the Terman method, and a slightly higher value was obtained as compared to the terman method.
Abstract: GaN metal oxide semiconductor diodes were demonstrated utilizing Sc 2 O 3 as the gate oxide. Sc 2 O 3 was grown at 100°C on MOCVD grown n-GaN layers in a molecular beam epitaxy system, using a scandium elemental source and an electron cyclotron resonance oxygen plasma. Ar/Cl 2 based discharges were used to remove Sc 2 O 3 , to expose the underlying n-GaN for ohmic metal deposition in an inductively coupled plasma system. Electron beam deposited Ti/Al/Pt/Au and Pt/Au were utilized as ohmic and gate metallizations, respectively. An interface trap density of 5 X 10 1 1 eV - 1 cm - 2 was obtained with the Terman method. Conductance-voltage measurements were also used to estimate the interface trap density and a slightly higher value was obtained as compared to the Terman method. Results of capacitance measurements at elevated temperature (up to 300°C) indicated the presence of deep states near the interface.

27 citations

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TL;DR: In this article, current transport mechanisms and persistent photoconductivity effects were studied in nitrogen-doped ZnO films grown by molecular beam epitaxy having p-type or n-type conductivity at 25°C.
Abstract: Current transport mechanisms and persistent photoconductivity effects were studied in nitrogen-doped ZnO films grown by molecular beam epitaxy having p-type or n-type conductivity at 25°C. In both types of samples the current flow is determined by the n-type channels surrounded by higher resistivity regions. The persistent photoconductivity wave form is reasonably described by the stretched-exponents-type expression, with only a slight temperature dependence of the characteristic decay time. The persistent photocurrent decay process is greatly accelerated by infrared illumination (threshold energy of the photons ∼1.4eV). The results suggest that the Fermi level in the higher resistivity regions is pinned near Ev+1.9±0.1eV and the height of the potential barrier for electrons in the n-type channels is around 1.4±0.1eV.

27 citations

Journal ArticleDOI
TL;DR: In this article, high ion density dry etching of bulk single-crystal β-Ga2O3 was carried out as a function of source power (100-800 W), chuck power (15-400 W), and frequency (13.56 or 40 W) in inductively coupled plasma (ICP) systems using Cl2/Ar or BCl3/Ar discharges.
Abstract: High ion density dry etching of bulk single-crystal β-Ga2O3 was carried out as a function of source power (100–800 W), chuck power (15–400 W), and frequency (13.56 or 40 MHz) in inductively coupled plasma (ICP) systems using Cl2/Ar or BCl3/Ar discharges. The highest etch rate achieved was ∼1300 A min−1 using 800 W ICP source power and 200 W chuck power (13.56 MHz) with either Cl2/Ar or BCl3/Ar. This is still a comfortably practical set of conditions, where resist reticulation does not occur because of the effective He backside cooling of the sample in the tool and the avoidance of overly high powers in systems capable of 2000 W of source power. The etching is ion-assisted and produces anisotropic pattern transfer. The etched surface may become oxygen-deficient under strong ion-bombardment conditions. Schottky diodes fabricated on these surfaces show increased ideality factors (increasing from 1.00 to 1.29 for high power conditions) and reduced barrier heights (1.1 on reference diodes to 0.86 eV for etched...

27 citations

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TL;DR: In this article, the use of photoluminescence spectroscopy to monitor epitaxial films of Al0.3Ga0.7As and semi-insulating GaAs substrates during BCl3 plasma etching and H2 plasma passivation was reported.
Abstract: Monitoring wafer changes in situ during plasma treatment provides real‐time feedback for developing and controlling device processing. In this letter we report the use of photoluminescence spectroscopy to monitor epitaxial films of Al0.3Ga0.7As and semi‐insulating GaAs substrates during BCl3 plasma etching and H2 plasma passivation. Photoluminescence monitoring is used for etching endpoint detection, surface damage quantification, and wafer temperature measurement.

27 citations

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TL;DR: In this article, the performance of Schottky rectifiers fabricated with dielectric overlap edge termination on epitaxial layers grown on a free-standing GaN template is reported.
Abstract: The performance of Schottky rectifiers fabricated with dielectric overlap edge termination on epitaxial layers grown on a free-standing GaN template is reported. The power figure-of-merit (VB)2/RON where VB is the reverse breakdown voltage and RON is the on-state resistance was 11.5 MW cm−2. The forward turn-on voltage was ∼3.5 V at 25 °C, with an on-state resistance of ∼5×10−3 Ω cm2. The reverse recovery time was ⩽50 ns in switching from forward bias to reverse bias. The reverse breakdown showed a temperature coefficient of −0.45 V/C.

27 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

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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