scispace - formally typeset
Search or ask a question
Author

Suzanne E. Mohney

Bio: Suzanne E. Mohney is an academic researcher from Pennsylvania State University. The author has contributed to research in topics: Ohmic contact & Contact resistance. The author has an hindex of 38, co-authored 226 publications receiving 5375 citations. Previous affiliations of Suzanne E. Mohney include Foundation University, Islamabad & University of Wisconsin-Madison.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, the early stages of thermal oxidation of gallium nitride epilayers in dry O 2 have been studied using surface sensitive analytical techniques and transmission electron microscopy.

80 citations

Journal ArticleDOI
TL;DR: Results suggest that Al is incorporated into the Si nanowires under these conditions at concentrations higher than the solubility limit (5-6 x 10(18) cm(-3)) for Al in Si at 550 degrees C.
Abstract: The synthesis of epitaxially oriented Si nanowires at high growth rates (>1 μm/min) was demonstrated on (111) Si substrates using Al as the catalyst. The use of high H2 and SiH4 partial pressures was found to be effective at reducing problems associated with Al oxidation and nanowire nucleation, enabling growth of high aspect ratio structures at temperatures ranging from 500 to 600 °C with minimal tapering of the diameter. Because of the high growth rate observed, the Al catalyst is believed to be in the liquid state during the growth. Four-point resistance measurements and back-gated current−voltage measurements indicate that the wires are p-type with an average resistivity of 0.01 ± 0.004 Ω-cm. These results suggest that Al is incorporated into the Si nanowires under these conditions at concentrations higher than the solubility limit (5−6 × 1018 cm−3) for Al in Si at 550 °C. This work demonstrates that Al can serve as both an effective catalyst and p-type dopant for the growth of Si nanowires.

79 citations

Journal ArticleDOI
TL;DR: In this paper, the authors systematically looked at four different Al-Ti alloy compositions in an attempt to decide which alloy if any is superior as an ohmic contact material to p-type SiC.
Abstract: Alloys of aluminum and titanium have been successfully used to form low resistance ohmic contacts to p-type SiC. While the 90 wt.% Al alloy has been studied extensively, the literature does not reveal any work which indicates whether the 90/10 or any other alloy composition is the best alloy for use as an ohmic contact material to p-SiC. This work systematically looks at four different Al–Ti alloy compositions in an attempt to decide which alloy if any is superior as an ohmic contact material. The alloy compositions that were studied were chosen by examining the binary Al–Ti phase diagram and choosing specific phases prior to reaction with the SiC. It will be shown that only alloys which have some amount of a liquid phase present at the anneal temperature will form an ohmic contact to p-type SiC.

76 citations

Journal ArticleDOI
TL;DR: In this paper, the oxidation of silicon nanowires with an average radius of 37nm was investigated using the vapor-liquid-solid technique with Au to mediate the growth of the nanowire.
Abstract: Silicon nanowires have received attention for nanoscale electronic devices and chemical and biological sensors. The thermal oxide grown on the silicon nanowires could be used in a variety of devices, so the oxidation of the silicon nanowires is investigated in this work. Silicon nanowires with an average radius of 37nm were grown for these experiments using the vapor-liquid-solid technique with Au to mediate the growth. Etching of the Au tips from the silicon nanowires was performed prior to oxidation to avoid local accelerated oxidation at the nanowire tip. Oxidation was performed at 700°C for 1–121h and at 650 and 750°C for 4h in O2, and the oxidized nanowires were examined by transmission electron microscopy. Depending on the conditions for oxidation, an oxide shell as thin as 6nm was observed, or the entire nanowire was oxidized. The kinetics of oxidation differ from those of a planar silicon wafer and are discussed in this work.

75 citations

Journal ArticleDOI
TL;DR: In this paper, the specific contact resistance of V/Al/Pt/Au and Ti/Al, Pt, and Au contacts to n-Al0.3Ga0.7N/GaN heterostructures is investigated.
Abstract: A study of V/Al/Pt/Au and Ti/Al/Pt/Au contacts to n-Al0.3Ga0.7N/GaN heterostructures is presented. Vanadium was chosen as a potential replacement for Ti because V is expected to form a thermally stable nitride with a low work function. Low-resistance Ohmic contacts are achieved with V/Al/Pt/Au layers after annealing at 650 °C, which represents a decrease of 150 °C compared to the Ti/Al/Pt/Au counterpart. This contact exhibits two orders of magnitude lower specific contact resistance compared to the Ti/Al/Pt/Au contacts studied in this work when annealed at temperatures less than 800 °C, although the specific contact resistance of the Ti/Al/Pt/Au contacts is lower when annealed at higher temperatures. A contact resistance and specific contact resistance of 0.8±0.1 Ω mm and (1.4±0.3)×10−5 Ω cm2, respectively, are obtained after annealing at 650 °C for 45 s.

71 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: The demonstration of these novel quantum-dot light-emitting diodes based on all-inorganic perovskite CsPbX3 (X = Cl, Br, I) nanocrystals opens a new avenue toward designing optoelectronic devices, such as displays, photodetectors, solar cells, and lasers.
Abstract: Novel quantum-dot light-emitting diodes based on all-inorganic perovskite CsPbX3 (X = Cl, Br, I) nanocrystals are reported. The well-dispersed, single-crystal quantum dots (QDs) exhibit high quantum yields, and tunable light emission wavelength. The demonstration of these novel perovskite QDs opens a new avenue toward designing optoelectronic devices, such as displays, photodetectors, solar cells, and lasers.

2,311 citations

Journal ArticleDOI
TL;DR: In this paper, the authors summarized the key advantages of using quantum dots as luminophores in light-emitting devices (LEDs) and outlined the operating mechanisms of four types of QD-LEDs.
Abstract: This Review article summarizes the key advantages of using quantum dots (QDs) as luminophores in light-emitting devices (LEDs) and outlines the operating mechanisms of four types of QD-LED. The key scientific and technological challenges facing QD-LED commercialization are identified, together with on-going strategies to overcome these challenges.

2,086 citations

Journal ArticleDOI
TL;DR: The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed in this article, along with the influence of process-induced or grown-in defects and impurities on the device physics.
Abstract: The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

1,693 citations

Journal ArticleDOI
TL;DR: The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed in this article.
Abstract: Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (e) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.

1,535 citations

Journal ArticleDOI
TL;DR: In this paper, the photocatalyst sheet design enables efficient and scalable water splitting using particulate semiconductors, which is a potentially scalable and economically feasible technology for converting solar energy into hydrogen.
Abstract: Photocatalytic water splitting using semiconductors is attractive for converting solar energy into hydrogen. An efficient and scalable system based on particulate photocatalyst sheets is now shown to exhibit energy conversion efficiency exceeding 1%. Photocatalytic water splitting using particulate semiconductors is a potentially scalable and economically feasible technology for converting solar energy into hydrogen1,2,3. Z-scheme systems based on two-step photoexcitation of a hydrogen evolution photocatalyst (HEP) and an oxygen evolution photocatalyst (OEP) are suited to harvesting of sunlight because semiconductors with either water reduction or oxidation activity can be applied to the water splitting reaction4,5. However, it is challenging to achieve efficient transfer of electrons between HEP and OEP particles6,7. Here, we present photocatalyst sheets based on La- and Rh-codoped SrTiO3 (SrTiO3:La, Rh; ref. 8) and Mo-doped BiVO4 (BiVO4:Mo) powders embedded into a gold (Au) layer. Enhancement of the electron relay by annealing and suppression of undesirable reactions through surface modification allow pure water (pH 6.8) splitting with a solar-to-hydrogen energy conversion efficiency of 1.1% and an apparent quantum yield of over 30% at 419 nm. The photocatalyst sheet design enables efficient and scalable water splitting using particulate semiconductors.

1,190 citations