We report high mechanical quality factors Q for GaN nanowire cantilevers grown by molecular beam epitaxy. Nanowires with 30–500nm diameters and 5–20μm lengths having resonance frequencies from 400kHzto2.8MHz were measured. near room temperature 10−4Pa ranged 2700 to above 60 000 most 10 000. Positive feedback a piezoelectric stack caused spontaneous oscillations exceeding 106. Spontaneous also occurred direct e-beam excitation of unintentionally doped nanowires. Doped nanowires showed no...

We report steady-state and time-resolved photoluminescence (TRPL) measurements on individual GaN nanowires (6–20 μm in length, 30–940 nm diameter) grown by a nitrogen-plasma-assisted, catalyst-free molecular-beam epitaxy Si(111) dispersed onto fused quartz substrates. Induced tensile strain for bonded to silica compressive coated with atomic-layer-deposition alumina led redshifts blueshifts of the dominant PL emission peak, respectively. Unperturbed exhibited spectra associated high-quality,...

The unique properties of GaN nanowires grown by molecular beam epitaxy are reviewed. These include the absence residual strain, exclusion most extended defects, long photoluminescence lifetime, low surface recombination velocity, and high mechanical quality factor. purity this method allows for controllable n-type doping. P-type doping presents more challenges but has been demonstrated in active light-emitting diode devices. present understanding nucleation growth these materials is also

Abstract The location of GaN nanowires is controlled with essentially perfect selectivity using patterned SiN x prior to molecular beam epitaxy growth. Nanowire growth uniform within mask openings and absent on the surface for over 95% usable area a 76 mm diameter substrate. diameters resulting are by size openings. Openings approximately 500 nm or less produce single symmetrically faceted tips.

Analysis of steady-state and transient photoconductivity measurements at room temperature performed on c-axis oriented GaN nanowires yielded estimates free carrier concentration, drift mobility, surface band bending, capture coefficient for electrons. Samples grown (unintentionally n-type) by nitrogen-plasma-assisted molecular beam epitaxy primarily from two separate growth runs were examined. The results revealed concentration in the range (3–6)×1016 cm−3 one run, roughly 5×1014–1×1015...

We characterized the elastic properties of GaN nanowires grown along different crystallographic orientations. In situ transmission electron microscopy tensile tests were conducted using a MEMS-based nanoscale testing system. Complementary atomistic simulations performed density functional theory and molecular dynamics. Our work establishes that elasticity size dependence is limited to with diameters smaller than 20 nm. For larger diameters, modulus converges bulk values 300 GPa for c-axis...

In this Letter we report on the fabrication, device characteristics, and optical coupling of a two-nanowire comprising GaN nanowires with light-emitting photoconductive capabilities. Axial p-n junction were grown by molecular beam epitaxy, transferred to non-native substrate, selectively contacted form discrete source or detector nanowire components. The demonstrated for may provide new opportunities integration interconnects between on-chip electrical subsystems.

Low-temperature AlN buffer layers grown via plasma-assisted molecular beam epitaxy on Si (111) were found to significantly affect the subsequent growth morphology of GaN nanowires. The exhibited nanowire-like columnar protrusions, with their size, shape, and tilt determined by V/III flux ratio. nanowires frequently observed adopt structural characteristics underlying columns, including size degree tilt. Piezoresponse force microscopy polarity-sensitive etching indicate that films protruding...

The field evaporation behavior of c-axis GaN nanowires was explored in two different laser-pulsed atom probe tomography (APT) instruments. Transmission electron microscopy imaging before and after analysis used to assist reconstructing the data assess observed behavior. It found that ionic species exhibited preferential locations for related underlying crystal structure which evaporated from these dependent on pulsed laser energy. Additionally, overall stoichiometry measured by APT...

We have demonstrated dramatic improvement in the quality of selective-area GaN nanowire growth by controlling polarity underlying nucleation layers. In particular, we find that N-polarity is beneficial for large ordered arrays with arbitrary spacing. Herein, present techniques obtaining and characterizing polarity-controlled layers on Si (111) substrates. An initial AlN layer, which to adopt Al- (N-)polarity N- (Al-)rich conditions, utilized configure subsequently grown as determined...

Nanowire–nanocluster hybrid chemical sensors were realized by functionalizing gallium nitride (GaN) nanowires (NWs) with titanium dioxide (TiO2) nanoclusters for selectively sensing benzene and other related aromatic compounds. Hybrid sensor devices developed fabricating two-terminal using individual GaN NWs followed the deposition of TiO2 RF magnetron sputtering. The fabrication process employed standard microfabrication techniques. X-ray diffraction high-resolution analytical transmission...

We demonstrate a new method for tailoring the selectivity of chemical sensors using semiconductor nanowires (NWs) decorated with metal and oxide multicomponent nanoclusters (NCs). Here we present change titanium dioxide (TiO(2)) nanocluster-coated gallium nitride (GaN) nanowire sensor devices on addition platinum (Pt) nanoclusters. The hybrid were developed by fabricating two-terminal individual GaN NWs followed deposition TiO(2) and/or Pt (NCs) sputtering technique. This paper sensing...

The first noncontact photoconductivity measurements of gallium nitride nanowires (NWs) are presented, revealing a high crystallographic and optoelectronic quality achieved by use catalyst-free molecular beam epitaxy. In comparison with bulk material, the NWs exhibit long conductivity lifetime (>2 ns) mobility (820 ± 120 cm(2)/(V s)). This is due to weak influence surface traps respect other III-V semiconducting favorable crystalline structure via strain-relieved growth.

A means of reproducibly fabricating stable cw lasers in rare-earth-doped Ti:LiNbO3 has been demonstrated through judicious choice waveguide orientation. Z-propagating waveguides have fabricated Nd- and Er-diffused room-temperature laser operation with greatly reduced photorefractive instability obtained. The damage susceptibility this configuration led to the realization a 980 nm pumped Er:Ti:LiNbO3, threshold 10.5 mW absorbed pump power slope efficiency 8.5%.

A prism coupling method was used to measure the ordinary (no) and extraordinary (ne) refractive indices of AlxGa1−xN films, grown by hydride vapor phase epitaxy (HVPE) metalorganic chemical deposition (MOCVD) on sapphire, at several discrete wavelengths from 442 nm 1064 nm. In addition, spectroscopic transmittance reflectance, correlated with results, were no as a continuous function wavelength between band gap each sample (255 364 nm, depending Al fraction) 2500 The mole fractions (x),...

We have demonstrated an array of monolithic, single-frequency-distributed-Bragg-reflector (DBR), waveguide lasers operating near 1536 nm wavelengths. The were fabricated by forming waveguides in Yb/Er-codoped phosphate glass ion exchange. slope efficiency for each laser as a function launched pump power is 26% and the thresholds occur at 50 mW power. An output 80 was achieved with 350 coupled Each exhibits stable operation on single longitudinal mode all linewidths less than 500 kHz. A comb...

Optical sum-frequency generation has been investigated in channel waveguides produced by proton exchange Mg-doped as well standard LiNbO3. Pyrophosphoric acid was used an media and Ta mask were patterned on z-cut plates reactive-ion etching to form diffusion apertures ranging width from 1 3 μm running parallel the y axis. Samples made direct immersion held at a temperature of 240 °C for times 10 28 min. End-fire coupling 1.06 revealed that Čerenkov radiation output second harmonic optimized...

In this paper, we demonstrate novel MESFETs based on individual GaN nanowires. The Pt/Au Schottky gates exhibited excellent two-terminal diode rectification behavior. average effective barrier height was 0.87 eV, with an ideality factor of 1.6. addition, the efficiently modulated conduction threshold gate voltages required for complete pinch off were as small -2.6 V, and transconductances exceeded 1.4 muS. Subthreshold swings approaching 60 mV/decade on/off current ratios up to 5times10 <sup...

Polarization- and temperature-dependent photoluminescence (PL) measurements were performed on individual GaN nanowires. These grown by catalyst-free molecular beam epitaxy Si(111) substrates, ultrasonically removed, subsequently dispersed sapphire substrates. The wires typically 5–10μm in length, c-axis oriented, 30–100nm diameter. Single produced sufficient emission intensity to enable high signal-to-noise PL data. Polarized spectra differed for the σ π polarization cases, illustrating...

Optimizing new generations of two-dimensional devices based on van der Waals materials will require techniques capable measuring variations in electronic properties situ and with nanometer spatial resolution. We perform scanning microwave microscopy (SMM) imaging single layers MoS2 n- p-doped WSe2. By controlling the sample charge carrier concentration through applied tip bias, we are able to reversibly control optimize SMM contrast image structure localized effects surface contaminants....