Unified Mechanism for Schottky-Barrier Formation and III-V Oxide Interface States

Spicer, W. E.; Lindau, I.; Skeath, Perry; Su, Ching‐Yuan; Chye, P.

doi:10.1103/physrevlett.44.420

Cited by 721 publications

(164 citation statements)

References 24 publications

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“…24 At V sd ) V g ) 0 V, the quantum dot is charged with 2 extra electrons caused by the Fermi level pinning at the nanowire surface. 18 At large positive backgate voltages (V g > 15 V), the emission stabilizes and a peak (line width of 160 µeV) at 1.3339 eV is observed. We assign this line to X 3-involving s-shell exciton recombination in the presence of three additional electrons.…”

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confidence: 98%

“…At the Ti-InP interface, the Fermi level is pinned ∼200 meV below the InP conduction band. 18 Therefore, Schottky barriers are formed and a source-drain voltage V sd generates an electric field along the nanowire growth axis without inducing a high current (I < 8 pA at V sd < 6 V). In addition, the charge density in the nanowire can be changed with the back-gate voltage V g .…”

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Single Electron Charging in Optically Active Nanowire Quantum Dots

Kouwen¹,

Reimer²,

Hidma³

et al. 2010

Nano Lett.

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We report optical experiments of a charge tunable, single nanowire quantum dot subject to an electric field tuned by two independent voltages. First, we control tunneling events through an applied electric field along the nanowire growth direction. Second, we modify the chemical potential in the nanowire with a back-gate. We combine these two field-effects to isolate a single electron and independently tune the tunnel coupling of the quantum dot with the contacts. Such charge control is a first requirement for opto-electrical single electron spin experiments on a nanowire quantum dot.KEYWORDS Nanowires, optically-active quantum dots, single electron charging, opto-electronics S ingle, optically active quantum dots are widely investigated due to the ability to combine both single electron charging 1,2 and single 3 or entangled 4 photonemission, which are all key requirements for quantum information processing applications. 5 Nanowire quantum dots (NW-QDs) offer additional functionalities over selfassembled quantum dots since they are embedded in a onedimensional system instead of a three-dimensional host matrix. Therefore, the single electron (hole) transport channel is naturally aligned to the optically active quantum dot in the nanowire, advantageous for combining both quantum optics 6 and transport. [7][8][9] In addition, due to the small radial dimensions of the nanowires, electrostatic gate geometries are highly versatile 7,8 and axial heterostructure design is not limited by strain. As an example, the combination of Si sections, which are free of nuclear spins, with optically addressable electronic levels in III-V materials is promising for extending electron spin storage times. Prior to the work presented here, we have shown that a single InAsP quantum dot grown in an InP nanowire geometry is optically active, exhibits narrow emission lines, spin polarization memory effects, 10 and can be embedded in a LED device geometry. 11 Furthermore, it is predicted that NW-QDs are ideal sources of entangled photons due to the nanowire symmetry. 12 Recently, an electron spin-to-charge conversion read-out scheme has been proposed, 13 which is compatible with controlled storage of carriers up to microseconds. 14 Such storage times are promising since single spins in selfassembled quantum dots (SA-QDs) have been initialized, coherently manipulated, and read-out within picosecond time scales. 15,16 The proposed spin read-out scheme 13 highly depends on the overall tunnel coupling between the SA-QD energy levels and the continuum, determined by the quantum dot-to-contact spatial separation, which is fixed during growth. 17 In this letter, we present electrical control and optical read-out of the number of electrons residing in a single InAs 0.25 P 0.75 quantum dot embedded in an InP nanowire. We first identify the neutral exciton by photocurrent spectroscopy. Second, we demonstrate that the electron number can be controlled by an electric field applied along the nanowire growth direction or by an electrostatic bac...

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Single Electron Charging in Optically Active Nanowire Quantum Dots

Kouwen¹,

Reimer²,

Hidma³

et al. 2010

Nano Lett.

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“…Of particular interest is the role of surface oxygen and hydroxyl, which are known to be present in high concentrations on exposed polar surfaces of many III-V semiconductors but are often neglected in idealized models, in part due to the complexity of the surface morphology. It has been suggested that the stability of some III-V surfaces in an electrolyte, as well as the photocatalytic water-splitting activity itself, may be tied to the existence of this surface oxygen 9,11,[13][14][15][16] . Such a connection between water splitting and surface oxygen is also consistent with our initial results on the InP(001)-water interface 17 .…”

Section: Introductionmentioning

confidence: 99%

Local structural models of complex oxygen- and hydroxyl-rich GaP/InP(001) surfaces

Wood

Ogitsu

Schwegler

2012

The Journal of Chemical Physics

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We perform density-functional theory calculations on model surfaces to investigate the interplay between the morphology, electronic structure, and chemistry of oxygen-and hydroxyl-rich surfaces of InP(001) and GaP(001). Four dominant local oxygen topologies are identified based on the coordination environment: M -O-M and M -O-P bridges for the oxygen-decorated surface; and M -[OH]-M bridges and atop M -OH structures for the hydroxyl-decorated surface (M =In,Ga). Unique signatures in the electronic structure are linked to each of the bond topologies, defining a map to structural models that can be used to aid the interpretation of experimental probes of native oxide morphology. The M -O-M bridge can create a trap for hole carriers upon imposition of strain or chemical modification of the bonding environment of the M atoms, which may contribute to the observed photocorrosion of GaP/InP-based electrodes in photoelectrochemical cells. Our results suggest that a simplified model incorporating the dominant local bond topologies within an oxygen adlayer should reproduce the essential chemistry of complex oxygen-rich InP(001) or GaP(001) surfaces, representing a significant advantage from a modeling standpoint.

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“…Although excellent device performances were achieved using high-j gate dielectrics on bulk (100)Ge and oxide/(100)Ge band alignment properties, little attention has been devoted on the integration of high-j gate dielectrics on the epitaxial (110)Ge, (111)Ge, and the associated energy band alignment at each interface. Moreover, finding a common high-j gate dielectric on epitaxial (100)Ge, (110)Ge, and (111)Ge layer is essential to eliminate the formation of high density intrinsic defects with energy levels in the semiconductor band gap 25 due to poor quality native oxides, resulting in Fermi level pinning 26 at the oxide-semiconductor interface. In this paper, we have investigated and compared the band alignment properties between the atomic layer deposited HfO 2 oxide film on the crystallographically oriented epitaxial Ge layer grown on (100)GaAs, (110)GaAs, and (111)A GaAs substrates using x-ray photoelectron spectroscopy (XPS) measurement.…”

Section: Introductionmentioning

confidence: 99%

Energy band alignment of atomic layer deposited HfO2 oxide film on epitaxial (100)Ge, (110)Ge, and (111)Ge layers

Hudait

Zhu

2013

Journal of Applied Physics

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Articles you may be interested inLow-temperature plasma-enhanced atomic layer deposition of HfO2/Al2O3 nanolaminate structure on Si J. Vac. Sci. Technol. B 33, 01A101 (2015) Crystallographically oriented epitaxial Ge layers were grown on (100), (110), and (111)A GaAs substrates by in situ growth process using two separate molecular beam epitaxy chambers. The band alignment properties of atomic layer hafnium oxide (HfO 2 ) film deposited on crystallographically oriented epitaxial Ge were investigated using x-ray photoelectron spectroscopy (XPS). Valence band offset, DE v values of HfO 2 relative to (100)Ge, (110)Ge, and (111)Ge orientations were 2.8 eV, 2.28 eV, and 2.5 eV, respectively. Using XPS data, variation in valence band offset, DE V ð100ÞGe > DE V ð111ÞGe > DE V ð110ÞGe, was obtained related to Ge orientation. Also, the conduction band offset, DE c relation, DE c ð110ÞGe > DE c ð111ÞGe > DE c ð100ÞGe related to Ge orientations was obtained using the measured bandgap of HfO 2 on each orientation and with the Ge bandgap of 0.67 eV. These band offset parameters for carrier confinement would offer an important guidance to design Ge-based p-and n-channel metal-oxide field-effect transistor for low-power application.

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Unified Mechanism for Schottky-Barrier Formation and III-V Oxide Interface States

Cited by 721 publications

References 24 publications

Single Electron Charging in Optically Active Nanowire Quantum Dots

Single Electron Charging in Optically Active Nanowire Quantum Dots

Local structural models of complex oxygen- and hydroxyl-rich GaP/InP(001) surfaces

Energy band alignment of atomic layer deposited HfO2 oxide film on epitaxial (100)Ge, (110)Ge, and (111)Ge layers

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