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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 thermal stability of dopant-hydrogen complexes in hydrogenated n and p-type GaAs (1−2×1017 cm−3) has been determined by examining their reactivation kinetics in reverse-biased Schottky diodes as mentioned in this paper.
Abstract: The thermal stability of dopant‐hydrogen complexes in hydrogenated n‐ and p‐type GaAs(1–2×1017 cm−3) has been determined by examining their reactivation kinetics in reverse‐biased Schottky diodes. The reactivation process is first‐order for all of the dopants, with thermal dissociation energies (ED) of 1.45±0.10 eV for SiAs acceptors, 1.25±0.05 eV for SiGa donors, 1.20±0.10 eV for SnGa donors, 1.25±0.10 eV for Zn acceptors, 1.35±0.05 eV for CAs acceptors, and 1.15±0.10 eV for Be acceptors. The dissociation frequencies (ν) are thermally activated of the form νD = ν0E−ED/kT, with the ν0 values in the range 1–5×1013 s−1. The results are consistent with much of the H being present as H+ in p‐type material, and H− in n‐type material.

42 citations

Journal ArticleDOI
TL;DR: In this article, the reactive ion etching of GaAs with a CCl2F2:O2 discharge was investigated as a function of gas flow rate (10−60 sccm), total pressure (2−50 mTorr), power density (0.25−1.31 W cm−2), gas composition (0%−70% O2), and etch time (1−64 min).
Abstract: The reactive ion etching of GaAs with a CCl2F2:O2 discharge was investigated as a function of gas flow rate (10–60 sccm), total pressure (2–50 mTorr), power density (0.25–1.31 W cm−2), gas composition (0%–70% O2), and etch time (1–64 min). The etch rate decreases with increasing gas flow rate, increases with increasing power density, and goes through a maximum at a gas composition of 75:25 CCl2F2:O2 under our conditions. After etching at low‐power densities (0.56 W cm−2) and for high CCl2F2 ratios (19:1 to O2), carbon and chlorine could be detected in the GaAs to a depth of less than 15 A by x‐ray photoelectron spectroscopy. Under these conditions there was a Ga deficiency to a depth of ∼100 A, which we ascribe to surface roughening and the preferential vaporization of As2O3 over Ga2O3. At high‐power densities (1.31 W cm−2) a polymeric layer several hundred angstroms thick containing CCl and CF bonds was observed on the GaAs surface. Etching under O2‐rich conditions did not lead to any additional creation...

42 citations

Journal ArticleDOI
TL;DR: In this paper, deep hole traps were studied in bulk free-standing GaN crystals and in thinner GaN films prepared by hydride vapor phase epitaxy (HVPE) on sapphire.
Abstract: Deep hole traps were studied in bulk free-standing GaN crystals and in thinner (10–20 μm) GaN films prepared by hydride vapor phase epitaxy (HVPE) on sapphire. Six hole traps in different combinations were detected in these crystals, H1 (activation energy 0.92–0.94 eV), H2 (0.55 eV), H3 (0.65–0.7 eV), H4 (0.85–0.9 eV), H5 (1.1–1.2 eV), and H6 (0.95–1.05 eV). The dominant traps in all samples were the H5 and H6 traps that were attributed, respectively, to gallium vacancy complexes with oxygen (VGa-O) and substitutional carbon related centers. We associate the H5 hole traps with the red luminescence bands, the H4 hole traps with the green luminescence bands, and the H6 hole traps with the yellow luminescence bands often observed in HVPE GaN. These attributions are based on the low energy thresholds of the deep traps optical excitation spectra and the depth of the respective trap levels.

42 citations

Patent
Fan Ren1, Stephen J. Pearton1, Tanmay P. Lele1, Hung-Ta Wang1, B. S. Kang1 
20 Mar 2009
TL;DR: In this article, high electron mobility transistors (HEMTs) with capture reagents on a gate region of the HEMTs are used for detecting breast cancer, prostate cancer, kidney injury, glucose, metals or pH where a signal is generated by HEMT when a solution is contacted with the sensor.
Abstract: Embodiments of the invention include sensors comprising high electron mobility transistors (HEMTs) with capture reagents on a gate region of the HEMTs. Example sensors include HEMTs with a thin gold layer on the gate region and bound antibodies; a thin gold layer on the gate region and chelating agents; a non-native gate dielectric on the gate region; and nanorods of a non-native dielectric with an immobilized enzyme on the gate region. Embodiments including antibodies or enzymes can have the antibodies or enzymes bound to the Au-gate via a binding group. Other embodiments of the invention are methods of using the sensors for detecting breast cancer, prostate cancer, kidney injury, glucose, metals or pH where a signal is generated by the HEMT when a solution is contacted with the sensor. The solution can be blood, saliva, urine, breath condensate, or any solution suspected of containing any specific analyte for the sensor.

42 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