All Outputs (38)

Molecular beam epitaxy as a growth technique for achieving free-standing zinc-blende GaN and wurtzite AlxGa1-xN (2017)
Journal Article

Currently there is a high level of interest in the development of ultraviolet (UV) light sources for solid state lighting, optical sensors, surface decontamination and water purification. III-V semiconductor UV LEDs are now successfully manufactured... Read More about Molecular beam epitaxy as a growth technique for achieving free-standing zinc-blende GaN and wurtzite AlxGa1-xN.

Deep ultraviolet emission in hexagonal boron nitride grown by high-temperature molecular beam epitaxy (2017)
Journal Article

Unintentional boron incorporation in AlGaN layers grown by plasma-assisted MBE using highly efficient nitrogen RF plasma-sources (2017)
Journal Article

Plasma-assisted molecular beam epitaxy (PA-MBE) is now widely used for the growth of group III-nitrides. Many years ago it became clear that during PA-MBE there is unintentional doping of GaN with boron (B) due to decomposition of the pyrolytic boron... Read More about Unintentional boron incorporation in AlGaN layers grown by plasma-assisted MBE using highly efficient nitrogen RF plasma-sources.

Intermixing studies in GaN_1−xSb_x highly mismatched alloys (2016)
Journal Article

GaN1−xSbx with x~ 5-7% is a highly mismatched alloy predicted to have favorable properties for application as an electrode in a photo-electrochemical cell for solar water splitting. In this study, we grew GaN1−xSbx under conditions intended to induce... Read More about Intermixing studies in GaN_1−xSb_x highly mismatched alloys.

Hexagonal Boron Nitride Tunnel Barriers Grown on Graphite by High Temperature Molecular Beam Epitaxy (2016)
Journal Article

We demonstrate direct epitaxial growth of high-quality hexagonal boron nitride (hBN) layers on graphite using high-temperature plasma-assisted molecular beam epitaxy. Atomic force microscopy reveals mono- and few-layer island growth, while conducting... Read More about Hexagonal Boron Nitride Tunnel Barriers Grown on Graphite by High Temperature Molecular Beam Epitaxy.

Growth of free-standing bulk wurtzite AlxGa1?xN layers by molecular beam epitaxy using a highly efficient RF plasma source (2016)
Journal Article

The recent development of group III nitrides allows researchers world-wide to consider AlGaN based light emitting diodes as a possible new alternative deep ultra–violet light source for surface decontamination and water purification. In this paper we... Read More about Growth of free-standing bulk wurtzite AlxGa1?xN layers by molecular beam epitaxy using a highly efficient RF plasma source.

X-ray detection with zinc-blende (cubic) GaN Schottky diodes (2016)
Journal Article

The room temperature X-ray responses as functions of time of two n type cubic GaN Schottky diodes (200 μm and 400 μm diameters) are reported. The current densities as functions of time for both diodes showed fast turn-on transients and increases in c... Read More about X-ray detection with zinc-blende (cubic) GaN Schottky diodes.

Highly mismatched GaN1−xSbxalloys: synthesis, structure and electronic properties (2016)
Journal Article

Highly mismatched alloys (HMAs) is a class of semiconductor alloys whose constituents are distinctly different in terms of size, ionicity and/or electronegativity. Electronic properties of the alloys deviate significantly from an interpolation scheme... Read More about Highly mismatched GaN1−xSbxalloys: synthesis, structure and electronic properties.

The UK National Quantum Technologies Hub in sensors and metrology (Keynote Paper) (2016)
Journal Article

The UK National Quantum Technology Hub in Sensors and Metrology is one of four flagship initiatives in the UK National of Quantum Technology Program. As part of a 20-year vision it translates laboratory demonstrations to deployable practical devices,... Read More about The UK National Quantum Technologies Hub in sensors and metrology (Keynote Paper).

Characterization of p-GaN1?xAsx/n-GaN PN junction diodes (2016)
Journal Article

The structural properties and electrical conduction mechanisms of p-type amorphous GaN1−xAsx/n-type crystalline GaN PN junction diodes are presented. A hole concentration of 8.5×1019 cm−3 is achieved which allows a specific contact resistance of 1.3×... Read More about Characterization of p-GaN1?xAsx/n-GaN PN junction diodes.

Surface acoustic wave velocity and elastic constants of cubic GaN (2016)
Journal Article

We present high-resolution surface Brillouin scattering measurements on cubic GaN layers grown on GaAs substrate. By using a suitable scattering geometry, scattering by surface acoustic waves is recorded for different azimuthal angles, and the surfac... Read More about Surface acoustic wave velocity and elastic constants of cubic GaN.

Strain-Engineered Graphene Grown on Hexagonal Boron Nitride by Molecular Beam Epitaxy (2016)
Journal Article

Graphene grown by high temperature molecular beam epitaxy on hexagonal boron nitride (hBN) forms continuous domains with dimensions of order 20 μm, and exhibits moiré patterns with large periodicities, up to ~30 nm, indicating that the layers are hig... Read More about Strain-Engineered Graphene Grown on Hexagonal Boron Nitride by Molecular Beam Epitaxy.

Molecular beam epitaxy of free-standing bulk wurtzite AlxGa1-xN layers using a highly efficient RF plasma source (2016)
Journal Article

Recent developments with group III nitrides suggest AlxGa1-xN based LEDs can be new alternative commer-cially viable deep ultra-violet light sources. Due to a sig-nificant difference in the lattice parameters of GaN and AlN, AlxGa1-xN substrates woul... Read More about Molecular beam epitaxy of free-standing bulk wurtzite AlxGa1-xN layers using a highly efficient RF plasma source.

Growth of free-standing wurtzite AlGaN by MBE using a highly efficient RF plasma source (2016)
Journal Article

Ultraviolet light emitting diodes (UV LEDs) are now being developed for various potential applications including water purification, surface decontamination, optical sensing, and solid-state lighting. The basis for this development is the successful... Read More about Growth of free-standing wurtzite AlGaN by MBE using a highly efficient RF plasma source.

High temperature MBE of graphene on sapphire and hexagonal boron nitride flakes on sapphire (2016)
Journal Article

The discovery of graphene and its remarkable electronic properties has provided scientists with a revolutionary material system for electronics and optoelectronics. Here, the authors investigate molecular beam epitaxy (MBE) as a growth method for gra... Read More about High temperature MBE of graphene on sapphire and hexagonal boron nitride flakes on sapphire.

Electronic band structure of highly mismatched GaN1?xSbx alloys in a broad composition range (2015)
Journal Article

In this letter, we study the optical properties of GaN1?xSbx thin films. Films with an Sb fraction up to 42% were synthesized by alternating GaN-GaSb layers at a constant temperature of 325 ?C. The measured optical absorption data of the films are in... Read More about Electronic band structure of highly mismatched GaN1?xSbx alloys in a broad composition range.

Anharmonic phonon decay in cubic GaN (2015)
Journal Article

We present a Raman scattering study of optical phonons in zincblende (cubic) GaN for temperatures ranging from 80 to 750 K. The experiments were performed on high quality, cubic GaN films grown by molecular beamepitaxy on GaAs (001) substrates. The o... Read More about Anharmonic phonon decay in cubic GaN.

Compositional variations in In0.5Ga0.5N nanorods grown by molecular beam epitaxy (2014)
Journal Article

The composition of InxGa1 ? xN nanorods grown by molecular beam epitaxy with nominal x = 0.5 has been mapped by electron microscopy using Z-contrast imaging and x-ray microanalysis. This shows a coherent and highly strained core-shell structure with... Read More about Compositional variations in In0.5Ga0.5N nanorods grown by molecular beam epitaxy.