This work provides experimental evidence and theoretical explanations regarding the formation mechanisms of GaN nanowires grown by selective area growth on GaN-on-sapphire templates. The first stage, driven kinetics, consists initial nucleation (along nanohole inner periphery), coalescence onset full coalescence, producing a single nanocrystal within each nanohole. In second free-surface-energy minimization, formed undergoes morphological evolution, exhibiting cylindrical-like shape,...

We present a study of the optical properties GaN/AlN and InGaN/GaN quantum dot (QD) superlattices grown via plasma-assisted molecular-beam epitaxy, as compared to their well (QW) counterparts. The three-dimensional/two-dimensional nature structures has been verified using atomic force microscopy transmission electron microscopy. QD higher internal efficiency respective QWs result three-dimensional carrier localization in islands. In QW samples, photoluminescence (PL) measurements point out...

A pencil-like morphology of homoepitaxially grown GaN nanowires is exploited for the fabrication thin conformal intrawire InGaN nanoshells which host quantum dots in nonpolar, semipolar and polar crystal regions. All three dot types exhibit single photon emission with narrow line widths high degrees linear optical polarization. The region strongly affects both wavelength lifetime, reaching subnanosecond time scales non- dots. Localization sites potential landscape, most likely induced by...

This work studies the effect of post-growth annealing on structural and optical properties copper oxide films. Thin films were obtained by 3D printing glass substrates using ink based a suspension CuO nanoparticles. To optimize their characteristics quality, samples subjected to thermal for 30 min in an argon environment at different temperatures from 250 °C 500 °C. The studied scanning electron microscopy, X-ray diffraction, energy dispersive X-Ray, Raman, photoelectric spectroscopy. Based...

Indium incorporation and surface morphology of InAlN layers grown on (0001) GaN by plasma-assisted molecular beam epitaxy were investigated as a function the impinging In flux substrate temperature in 450–610 °C range. was found to decrease with due thermal decomposition growing layer, while for given it increased until stoichiometry reached at growth front. The InN losses during followed an Arrhenius behavior characterized activation energy 2.0 eV. A diagram highly instrumental identify...

A uniformly n-type doped GaN:Si nanowire (NW), with a diameter of d = 90 nm and length 1.2 μm, is processed into metal-semiconductor field effect transistor (MESFET) semi-cylindrical top Ti/Au Schottky gate. The FET in normally-ON mode, the threshold at −0.7 V transconductance gm ∼ 2 μS (the normalized NW gm/d > 22 mS/mm). It enters saturation mode VDS 4.5 V, maximum measured drain current IDS 5.0 μA density exceeding JDS 78 kA/cm2.

We report on properties of high quality ∼60 nm thick InAlN layers nearly in-plane lattice-matched to GaN, grown c-plane GaN-on-sapphire templates by plasma-assisted molecular beam epitaxy. Excellent crystalline and low surface roughness are confirmed X-ray diffraction, transmission electron microscopy, atomic force microscopy. High annular dark field observations reveal a periodic indium content variation (8 period), whereas optical measurements evidence certain residual absorption below the...

Single-photon emitters (SPEs) are at the basis of many applications for quantum information management. Semiconductor-based SPEs best suited practical implementations because high design flexibility, scalability and integration potential in devices. emission from ordered arrays InGaN nano-disks embedded GaN nanowires is reported. Intense narrow optical lines dot-like recombination centers observed blue-green spectral range. Characterization by electron microscopy, cathodoluminescence...

Theoretical modelling of the intraband absorption spectrum in InAs/GaAs quantum dot infrared photodetectors is performed for several typical structures reported literature. The calculations are within framework two methods: a simple and so far widely used effective mass method with values conduction band offset modified to take account effects strain mixing on average more realistic eight-band k × p distribution taken into via continuum mechanical model. Both methods give qualitatively same...

Abstract High-resolution monochromated electron energy loss spectroscopy (EELS) at subnanometric spatial resolution and <200 meV has been used to assess the valence band properties of a distributed Bragg reflector multilayer heterostructure composed InAlN lattice matched GaN. This work thoroughly presents collection methods computational tools put together for this task. Among these are zero-loss-peak subtraction nonlinear fitting tools, theoretical modeling scattering distribution. EELS...

In this work, through a comparative study of self-assembled (SA) and selective area grown (SAG) (In)GaN nanocolumn (NC) ensembles, we first give detailed insight into improved crystallographic uniformity (homogeneity tilts twists) the latter ones. The study, performed making use of: reflective high energy electron diffraction, X-ray diffraction scanning microscopy, reveals that unlike their SA counterparts, ensembles SAG NCs show single epitaxial relationship to both sapphire(0001) Si(111)...

Series of GaN nanowires (NW) with controlled diameters (160–500 nm) and heights (420–1100 were homoepitaxially grown on three different templates: GaN/Si(111), GaN/AlN/Si(111), GaN/sapphire(0001). Transmission electron microscopy reveals a strong influence the NW diameter dislocation filtering effect, whereas photoluminescence measurements further relate this effect to NWs near-bandgap emission efficiency. Although templates' quality has some effects optical structural properties, reduction...

This work reports an experimental and theoretical insight into phenomena of two-color emission different electron-hole recombination dynamics in InGaN nanodisks, incorporated pencil-like GaN nanowires. The studied nanodisks consist one polar (on $c$ facet) six (nominally) identical semipolar $r$ facets) sections, as confirmed by transmission electron microscopy. combination cathodoluminescence with scanning microscopy spatially resolves the nanodisk emission, low-energy (\ensuremath{\sim}500...

We report on molecular beam epitaxy growth and characterization of ten-period lattice-matched InAlN/GaN distributed Bragg reflectors (DBRs), with peak reflectivity centered around 400 nm. Thanks to the well tuned ternary alloy composition, crack-free surfaces have been obtained, as confirmed by both optical transmission electron microscopy (TEM). Their good periodicity well-defined interfaces x-ray diffraction TEM measurements. Peak values high 60% stop bands 30 nm demonstrated. Optical...

The optical emission of InGaN quantum dots embedded in GaN nanowires is dynamically controlled by a surface acoustic wave (SAW). energy both the exciton and biexciton lines modulated over 1.5 meV range at ~330 MHz. A small but systematic difference spectral modulation reveals linear change binding with SAW amplitude. present results are relevant for dynamic control individual single photon emitters based on nitride semiconductors.

This work gives a detailed insight into how the formation of (Al,Ga)N transient layers (TLs) at interfaces AlN/GaN Bragg reflectors modifies their structural and optical properties. While abrupt are typically characterized with network microcracks, those TLs nanocracks. Transmission electron microscopy reveals strong correlation between strain thickness, identifying thus as driving force for formation. The intermixing preserves targeted stopband position (∼410 nm), whereas peak reflectivity...

A 3λ/2 (In,Ga)N/GaN resonant cavity, designed for ∼415 nm operation, is grown by molecular beam epitaxy and sandwiched between a 39.5-period (In,Al)N/GaN distributed Bragg reflector (DBR), on c-plane GaN-on-sapphire pseudo-substrate metal-organic vapor phase an 8-period SiO2/ZrO2 DBR, deposited electron evaporation. Optical characterization reveals improvement in the cavity emission spectral purity of approximately one order magnitude due to resonance effects. The combination...

Abstract III-V nitride (AlGa)N distributed Bragg reflector devices are characterized by combined high-angle annular dark-field (HAADF) and electron energy loss spectroscopy (EELS) in the scanning transmission microscope. Besides complete structural characterization of AlN GaN layers, formation AlGaN transient layers is revealed using Vegard law on profiles position bulk plasmon peak maximum. This result confirmed comparison experimental simulated HAADF intensities. In addition, we present an...

The realization of reliable single photon emitters operating at high temperature and located predetermined positions still presents a major challenge for the development solid-state systems quantum light applications. We demonstrate single-photon emission from two-dimensional ordered arrays GaN nanowires containing InGaN nanodisks. structures were fabricated by molecular beam epitaxy on (0001) GaN-on-sapphire templates patterned with nanohole masks prepared colloidal lithography....

Abstract We demonstrate six to ten period lattice‐matched In 0.18 Al 0.82 N/GaN distributed Bragg reflectors with peak reflectivity centred around 400 nm, grown by molecular beam epitaxy. Thanks the well‐tuned ternary alloy composition crack‐free layers have been obtained as confirmed both optical and scanning electron microscopy. addition, cross‐sectional analysis high resolution transmission microscopy reveals highly periodic structure abrupt interfaces. When number of DBRs periods...

InN quantum dots (QDs) are considered to be promising nanostructures for different device applications. For any hexagonal AB stacking semiconductor system, polarity is an important feature which affects the electronic properties. Therefore, determination of this characteristic on wurtzite (semi)polar III nitride compound or alloy essential defining its applicability. In paper, QDs grown silicon by indium droplet epitaxy plus nitridation and annealing was determined a modified approach...