Snezana Lazic

Universidad Autónoma de Madrid | UAM · Departamento de Física de Materiales, Facultad de Ciencias

Hexagonal boron nitride (hBN) is attracting a lot of attention in the last years, thanks to its many remarkable properties. These include the presence of single-photon emitters with superior optical properties, which make it an ideal candidate for a plethora of photonic technologies. However, despite the large number of experimental results and the...

Hexagonal boron nitride (hBN) has attracted a lot of attention in the past years, thanks to its many remarkable properties. These include the presence of single‐photon emitters with superior optical properties, which make it an ideal candidate for a plethora of photonic technologies. However, despite the large number of experimental results and the...

We analyse the morphological, structural and luminescence properties of self-assembled ZnO nanowires grown by chemical vapour transport on Si(001). The examination of nanowire ensembles by scanning electron microscopy reveals that a non-negligible fraction of nanowires merge together forming coalesced aggregates during growth. We show that the coal...

We analyse the morphological, structural and luminescence properties of self-assembled ZnO nanowires grown by chemical vapour transport on Si(001). The examination of nanowire ensembles by scanning electron microscopy reveals that a non-negligible fraction of nanowires merge together forming coalesced aggregates during growth. We show that the coal...

We show the efficiency in the preparation of >95 % dense ZnO ceramics by cold sintering process through the incorporation of ZnO nanoparticles in the 1−10 wt% range at temperatures of 170 °C, pressures of 750 MPa and a pellet height/diameter ratio of 0.38. Morphological, structural and physical properties are dependent on the amount of ZnO nanopart...

Taking advantage of the flexibility of the apatite structure, nano- and micro-particles of hydroxyapatite (HAp) were doped with different combinations of rare earth ions (RE3+ = Gd, Eu, Yb, Tm) to achieve a synergy among their magnetic and optical properties and to enable their application in preventive medicine, particularly diagnostics based on m...

Luminescent defects in hexagonal boron nitride (h-BN) have recently emerged as a promising platform for non-classical light emission. On-chip solutions, however, require techniques for controllable in-situ manipulation of quantum light. Here, we demonstrate the dynamic spectral and temporal tuning of the optical emission from h-BN via moving acoust...

On-chip quantum information processing requires controllable quantum light sources that can be operated on-demand at high-speeds and with the possibility of in-situ control of the photon emission wavelength and its optical polarization properties. Here, we report on the dynamic control of the optical emission from core-shell GaN/InGaN nanowire (NW)...

We report on experimental studies of the effects induced by surface acoustic waves on the optical emission dynamics of GaN/InGaN nanowire quantum dots. We employ stroboscopic optical excitation with either time-integrated or time-resolved photoluminescence detection. In the absence of the acoustic wave, the emission spectra reveal signatures origin...

We report on experimental study into the effects of surface acoustic waves on the optical emission of dot-in-a-nanowire heterostructures in III-V material systems. Under direct optical excitation, the excitonic energy levels in III-nitride dot-in-a-nanowire heterostructures oscillate at the acoustic frequency, producing a characteristic splitting o...

A pencil-like morphology of homoepitaxially grown GaN nanowires is exploited for the fabrication of thin conformal intra-wire InGaN nanoshells which host quantum dots in nonpolar, semipolar and polar crystal regions. All three quantum dot types exhibit single photon emission with narrow emission linewidths and high degrees of linear optical polariz...

The optical emission of InGaN quantum dots embedded in GaN nanowires is dynamically controlled by a surface acoustic wave (SAW). The emission energy of both the exciton and biexciton lines is modulated over a 1.5 meV range at ∼330 MHz. A small but systematic difference in the exciton and biexciton spectral modulation reveals a linear change of the...

Single-photon emitters (SPEs) are at the basis of many applications for quantum information management. Semiconductor-based SPEs are best suited for practical implementations because of high design flexibility, scalability and integration potential in practical devices. Single-photon emission from ordered arrays of InGaN nano-disks embedded in GaN...

The realization of reliable single photon emitters operating at high temperature and located at predetermined positions still presents a major challenge for the development of solid-state systems for quantum light applications. We demonstrate single-photon emission from two-dimensional ordered arrays of GaN nanowires containing InGaN nanodisks. The...

The realization of reliable single photon emitters operating at high temperature and located at predetermined positions still presents a major challenge for the development of solid-state systems for quantum light applications. We demonstrate single-photon emission from two-dimensional ordered arrays of GaN nanowires containing InGaN nano-disks. Th...

Present semiconductor technologies allow the growth of different types of nanostructures, such as quantum wells, wires, and dots on the surface of a single semiconductor crystal. The piezoelectric field of surface acoustic waves (SAWs) propagating on the crystal surface provides an efficient mechanism for the controlled exchange of electrons and ho...

We report on the modulation of indirect excitons (IXs) as well as their transport by moving periodic potentials produced by surface acoustic waves (SAWs). The potential modulation induced by the SAW strain modifies both the band gap and the electrostatic field in the quantum wells confining the IX, leading to changes in their energy. In addition, t...

Excitons, quasi-particles consisting of electron-hole pairs bound by the Coulomb interaction, are a potential medium for processing of photonic information in the solid-state. Information processing via excitons requires efficient techniques for the transport and manipulation of these uncharged particles. We introduce here a novel concept for the i...

Excitons, quasiparticles consisting of electron-hole pairs bound by the Coulomb interaction, are a potential medium for the processing of photonic information in the solid state. Information processing via excitons requires efficient techniques for the transport and manipulation of these uncharged particles. We have carried out a detailed investiga...

We demonstrate an information transfer mechanism between two dissimilar remote InAs/GaAs quantum dots weakly coupled to a common photonic crystal microcavity. Bichromatic excitation in the s-state of one of the dots leads to the formation of dressed states due to the coherent coupling to the laser field, in resonance with the quantum dot. Informati...

We report on resonant inelastic light scattering in dilute AlGaAsN films. Intense narrow peaks associated to N-related local vibration modes (LVM) have been observed around 325, 385, 400, 450, 500 and 540 cm−1. Their frequencies are compared to density functional theory supercell calculations of AlnGa4−nN complexes (n=1−4). We find clear indication...

We employ surface acoustic waves (SAWs) to control the transfer of photo-generated carriers between interconnected quantum wells and quantum wires (QWRs) grown on pre-patterned (311)A GaAs substrates. Optical studies, carried out under remote acoustic excitation of a single QWR, have shown sharp photoluminescence lines and antibunched photons with...

The oscillating piezoelectric field of a surface acoustic wave (SAW) is employed to transport photoexcited carriers, as well as to spatially control exciton recombination in GaAs-based nanowires (NWs) on a subns time scale. The experiments are carried out in core-shell NWs transferred to a SAW delay line on a LiNbO(3) crystal. Carriers generated in...

We employ surface acoustic waves to control the transfer of photo-generated carriers between interconnected quantum wells and wires grown on pre-patterned (311)A GaAs substrates. The wires are embedded at photo-lithographically defined positions within (Al,Ga)As/GaAs quantum well. Optical studies on these structures have shown sharp PL lines and an...

Time-resolved Kerr reflectometry (TRKR) is used to investigate the long-range transport of spins by surface acoustic waves in undoped GaAs (110) quantum wells. TRKR measurements under an applied magnetic field demonstrate the coherent precession of the optically generated electron spin during acoustic transport over several micrometers and yield in...

We demonstrate the controlled transfer of photoexcited carriers by a surface acoustic wave (SAW) between coupled quantum wells, wires, and dots grown on a semiconductor surface. The quantum wires and dots used in the experiments are embedded at photolithographically defined positions within an (Al,Ga)As/GaAs (311)A-oriented quantum well grown by mo...

Spatially resolved photoluminescence spectroscopy was employed to investigate the dynamic control of excitons in GaAs/AlGaAs double quantum wells within the confined and moving potentials formed by the interference of orthogonal surface acoustic waves. We demonstrate the unique ability of these dynamic strain dots to transport photogenerated indire...

Inelastic light scattering measurements on single crystal InN nanocolumns grown by plasma-assisted molecular beam epitaxy on both Si(001) and Si(111) substrates reveal the existence of a surface electron accumulation layer in the lateral non-polar sidewalls of the nanocolumns. Small and reversible electron density variations of this surface layer h...

We review recent results on the control and manipulation of carriers by surface acoustic waves in (Al,Ga)As nanostructures as well as applications of acoustic transport in single-photon detectors and emitters for quantum information processing.

Although extensive research on nanostructures has led to the discovery of a number of efficient ways to confine carriers in reduced dimensions, little has been done to make use of the unique properties of various nanostructured systems through coupling by means of the controllable transfer of carriers between them. Here, we demonstrate a novel appr...

Raman measurements on high quality, relaxed InN nanocolumns grown on Si(001) and Si(111) substrates by plasma-assisted molecular beam epitaxy are reported. A coupled LO phonon-plasmon mode around 430 cm–1, together with the uncoupled LO phonon appears in the nanocolumnar samples. The coupled mode is attributed to spontaneous accumulation of electro...

Raman scattering measurements in dilute AlGaAs:N films grown by plasma-assisted molecular beam epitaxy on (100) GaAs substrates reveal strong local vibration modes (LVM) associated to N complexes. The LVM observed frequencies between 325 and 540 cm–1 are in good agreement with density functional theory supercell calculations of AlnGa4–nN complexes...

Raman measurements in high-quality InN nanocolumns and thin films grown on both Si(l 1 1) and Si(l 00) substrates display a low- energy coupled LO phonon-plasmon mode together with uncoupled longitudinal optical (LO) phonons. The coupled mode is attributed to the spontaneous accumulation of electrons on the lateral surfaces of the nanocolumns, whil...

We report on resonant inelastic light scattering in dilute AlGaAsN films. Intense narrow peaks associated to N-related local vibration modes (LVM) have been observed around 325, 385, 400, 450, 500 and 540cm−1. Their frequencies are compared to density functional theory supercell calculations of AlnGa4−nN complexes (n=1−4). We find clear indications...

The localized vibrational modes associated with substitutional aluminium and nitrogen atoms in Al(y)Ga(1-y)N(x)As(1-x) have been studied within first-principles density functional theory using a supercell approach. Localized vibrational modes related to N-Al(m)Ga(4-m) (1 <= m <= 4) complexes have been identified, which reveal the formation of N-Al(...

Raman measurements in high quality InN nanocolumns display a coupled LO phonon-plasmon mode together with uncoupled phonons. The coupled mode is attributed to the spontaneous accumulation of electrons on the lateral surfaces of the nanocolumns. For increasing growth temperature, the electron density decreases as the growth rate increases. The prese...

A review of inelastic light scattering measurements on group III-nitride nanocolumns grown by molecular beam epitaxy is presented. The nanocolumns are hexagonal, high quality single crystals with diameters in the range of 20 to 100 nm, with no traces of extended defects. GaN nanocolumns grown on bare Si substrates with both (111) and (100) orientat...

We have studied the vibrational properties of hexagonal InN nanocolumns and compact layers. Depending on the sample structure the Raman active phonon bands of InN corresponding to the E2, A1(LO) and E1(LO) modes were observed. In addition, the weak and broad feature at 429 cm-1 detected in the columnar sample was assigned to the low energy E1(LO) p...

InxGa1-xAs1-yNy/Al0.33Ga0.67As multiquantum wells grown by plasma-assisted molecular beam epitaxy are studied by resonant inelastic light scattering. Sharp vibration modes have been observed at 323, 402, 454 and 501 cm-1. Their intensities resonate at the barrier bandgap reduced by the presence of N. Their resonance energies reveal the influence of...

Wurtzite single crystal GaN nanocolumns were grown by plasma-assisted molecular beam epitaxy on bare Si(001) substrates. Nanocolumns with diameters in the range of 20–40 nm have no traces of extended defects and they grow aligned along the [0001] direction. Photoluminescence measurements in nanocolumns evidence a very high crystal quality in terms...

This work reports on the morphology and optical properties of wurtzite InN layers grown by plasma assisted molecular beam epitaxy (PA-MBE) on Si(111) substrates. The layer morphology can be controlled by the effective indium to nitrogen molecular flux ratio, from N-rich conditions that lead to InN nanorods, to stoichiometric conditions leading to c...

We report resonant Raman scattering measurements on InGaAsN/AlGaAs multiquantum wells grown by plasma-assisted molecular beam epitaxy. Sharp vibration modes have been observed at 323, 402, 454 and 501 cm–1. They are resonant in the energy range 1.81–1.87 eV at decreasing energies for increasing N concentration. The resonance energies reveal the inf...

We report resonant Raman scattering and secondary ion mass spectrometry measurements on InGaAsN/AlGaAs multiquantum wells grown by plasma-assisted molecular beam epitaxy. The appearance of a strong TO band at resonance with nitrogen (N)-related electronic levels has been observed. The N-induced vibration mode at 470cm−1 changes in intensity and sha...

InxGa1-xAs1-yNy/Al 0.33Ga0.67As multiquantum wells grown by plasma-assisted molecular beam epitaxy are studied by resonant inelastic light scattering, Sharp vibration modes have been observed at 323, 402, 454 and 501 cm-1. Their intensities resonate at the barrier bandgap reduced by the presence of N. Their resonance energies reveal the influence o...

We present resonant Raman scattering measurements on strained and relaxed InxGa1-xN/GaN multiple quantum wells. The pseudomorphic sample does not show significant deviation of the A1(LO) phonon frequency with respect to GaN value due to a strong compensation of composition and strain effects which makes the frequency of this mode almost independent...

Resonant Raman scattering measurements on In0.15Ga0.85N/GaN multiquantum wells are reported. Depending on their width, the multiquantum wells are either fully strained or relaxed, as shown by the Raman frequency of the A1(LO) phonon. In the strained sample, the A1(LO) frequency shows no significant deviation from the GaN value, as the effects of I...

We present resonant Raman scattering measurements on strained and relaxed InxGa1-xN/GaN multiple quantum wells. The pseudomorphic sample does not show significant deviation of the A(1)(LO) phonon frequency with respect to GaN value due to a strong compensation of composition and strain effects which makes the frequency of this mode almost independe...

The effects of the composition and strain in InGaN/GaN multi-quantum wells on their phonon frequencies have been determined using resonant Raman scattering in a wide energy range. In pseudomorphic quantum wells a strong compensation of both effects occurs, resulting in the InGaN A1LO phonon frequency being almost independent on In concentration. In...