Strain Modulation of Si Vacancy Emission from SiC Micro- and Nanoparticles.

Single-photon emitting point defects in semiconductors have emerged as strong candidates for future quantum technology devices. In the present work, we exploit crystalline particles to investigate relevant defect localizations, emission shifting, and waveguiding. Specifically, emission from 6H-SiC micro- and nanoparticles ranging from 100 nm to 5 µm in size is collected using cathodoluminescence (CL), and we monitor signals attributed to the Si vacancy (VSi) as a function of its location. Clear shifts in the emission wavelength are found for emitters localized in the particle center and at the edges. By comparing spatial CL maps with strain analysis carried out in transmission electron microscopy, we attribute the emission shifts to compressive strain of 2-3% along the particle a-direction. Thus, embedding VSi qubit defects within SiC nanoparticles offers an interesting and versatile opportunity to tune single-photon emission energies while simultaneously ensuring ease of addressability via a self-assembled SiC nanoparticle matrix.

Silicon surface passivation by PEDOT: PSS functionalized by SnO2 and TiO2 nanoparticles.

In this paper, we present a study of silicon surface passivation based on the use of spin-coated hybrid composite layers. We investigate both undoped poly(3,4-ethylenedioxythiophene)/poly-(styrenesulfonate) (PEDOT:PSS), as well as PEDOT:PSS functionalized with semiconducting oxide nanomaterials (TiO2 and SnO2). The hybrid compound was deposited at room temperature by spin coating-a potentially lower cost, lower processing time and higher throughput alternative compared with the commonly used vacuum-based techniques. Photoluminescence imaging was used to characterize the electronic properties of the Si/PEDOT:PSS interface. Good surface passivation was achieved by PEDOT:PSS functionalized by semiconducting oxides. We show that control of the concentration of semiconducting oxide nanoparticles in the polymer is crucial in determining the passivation performance. A charge carrier lifetime of about 275 µs has been achieved when using SnO2 nanoparticles at a concentration of 0.5 wt.% as a filler in the composite film. X-ray diffraction (XRD), scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive x-ray in an SEM, and µ-Raman spectroscopy have been used for the morphological, chemical and structural characterization. Finally, a simple model of a photovoltaic device based on PEDOT:PSS functionalized with semiconducting oxide nanoparticles has been fabricated and electrically characterized.

Study of mechanical resonances of Sb2O3 micro- and nanorods.

Sb2O3 microrods with orthorhombic phase were grown by an evaporation-deposition method from a pure antimony source and substrate. The incorporation of Cr into the substrate has been found to enhance the growth of thinner rods with high crystalline quality, as is revealed by high resolution transmission electron microscopy (HRTEM). Electric field-induced mechanical resonances of Sb2O3 nanorods were studied by in situ measurements in a scanning electron microscope (SEM). Young's modulus of rods with different lengths and cross-sectional dimensions was calculated from the resonance frequency. The E values for the different rods were in the range of 16-48 GPa. For comparison, Young's moduli of several rods were also measured from the force-displacement curve recorded in an atomic force microscope (AFM). The slight difference between the E values obtained by the resonance and by the AFM techniques is within the accepted experimental error.

Electrical properties of nanostructured tin oxide surfaces produced by thermal treatments.

Sintering SnO2 powder in air or under an oxygen atmosphere at different temperatures, leads to polycrystalline samples with nanostructured surface as revealed by atomic force microscopy (AFM). The thermal treatments are also responsible for the variation of the surface electrical properties, as studied by scanning spreading resistance microscopy (SSRM) and scanning tunnelling microscopy and spectroscopy (STM-STS). The surface presents a p-conductance, contrary to the n-type characteristic of the bulk, and a band gap lower than the bulk band gap (3.6 eV). The electrical behaviour at the grain boundaries and the role of oxygen are discussed. X-ray photoelectron spectroscopy (XPS) results show a higher presence of oxygen at the boundaries, which generates a shift of the Fermi level position (E(F)-E(V)) towards lower energies.

Growth and luminescence of N doped TiO2 nanowires.

Titanium oxide nanowires have been grown by thermal treatment of pressed TiN powder under argon or N2 flow. It has been found that two-step treatments at two different temperatures, 400 degrees C and 800 degrees C, lead to the growth of nanowires all over the sample surface. The nanowires are of single crystalline rutile structure. Energy dispersive X-ray spectroscopy and photoelectron spectroscopy measurements show that the oxide nanostructures contain N from the starting nitride. The mechanism of N incorporation into the oxide and its possible effect on the luminescence are discussed.

Cathodoluminescence study of semiconductor oxide micro- and nanostructures grown by vapor deposition.

Nano- and microstructures of SnO(2), In(2)O(3) and ZnO have been grown during thermal treatment of compacted powders under argon flow. Indium-doped SnO(2) tube-shaped structures with rectangular cross-section are obtained by adding a fraction of In(2)O(3) to the starting SnO(2) powder. In-rich nanoislands were found to grow on some edges of the tubes. ZnO nanostructures doped with Sn or Eu were grown by adding SnO(2) and Eu(2)O(3) powder, respectively, to the ZnO precursor powder. All the samples have been characterized by the emissive and cathodoluminescence (CL) modes of scanning electron microscopy. CL images from SnO(2):In and In(2)O(3):Sn tubes and islands show a higher emission from the Sn-rich structures related to oxygen deficiency. CL of doped ZnO enables to detect the presence of dopant in specific regions or structures. CL appears to be a useful technique to study optical and electronic properties of semiconductor oxide nanostructures.

Formation and luminescence of nanoterraces and elongated structures in sintered TiO2.

Samples of rutile TiO2 have been prepared by sintering compacted powders under argon flow. Long (above 20 h) sintering times at 1500 °C led to the formation of rods with squared cross-sections in a broad range of sizes. A two-step annealing treatment, at two temperatures, was found to favour the growth of low-dimensional elongated structures as well as a terraced structure on the grain surface, producing samples with high surface to volume ratio. The cathodoluminescence (CL) spectrum of the initial powder, shows an emission centred at about 2.40 eV, which can be separated into three Gaussian bands at 2.19, 2.30 and 2.55 eV. The main features of the CL spectra of sintered samples are an infrared band at 1.52 eV and a complex band in the visible range, whose peak position shifts with the annealing temperature. In samples sintered for 30 h an emission at 1.80 eV appears, while the dominant emission at 1.52 eV, due to titanium interstitials, is quenched.

[Programme to overcome tobacco dependency in cases of scheduled surgery]. / Programa de deshabituación tabáquica en cirugía programada.

INTRODUCTION AND OBJECTIVES: Tobacco dependency is now beginning to be seen as a chronic disease. The scientific evidence of the damage it causes and the existence of efficient interventions mean it has to be tackled. In Health Area VIII of Asturias a plan to aid smokers was initiated in 1998. Now we want to extend this to patients who are going to have scheduled surgery, since it has been demonstrated that tobacco increases post-operative complications. In addition, having to confront surgery may be a reason for trying to give up tobacco. ACTIVITIES: Patients who are going to undergo surgery will be questioned and counselled on their tobacco habit during the pre-operative period. They will do the Richmond test and will be referred to the health centre if their score is >= 7.Interventions. The family doctor assesses the smokers' dependency and motivation, and offers them personalised treatment to give up. During their time in hospital, a nurse backs up their non-smoking. Once discharged, they are monitored periodically in primary care. EVALUATION: At the same time as the annual evaluation of the service portfolio, the number of smokers who underwent surgery and were counselled, visited on the ward and monitored in primary care will be measured. The number of patients still not smoking at one month, six months and twelve months will be recorded. CONCLUSIONS: Lack of finance for the treatment may be one of the limitations of the programme. Although there are experiences in other countries of interventions in smokers who are going to have surgery, we have found no similar programme here.

Programa de deshabituación tabáquica en cirugía programada / Programme to overcome tobacco dependency in cases of schedule surgery

Introducción y objetivos. Actualmente el tabaquismo empieza a ser considerado una enfermedad crónica. La evidencia científica de los daños que produce y la existencia de intervenciones eficientes hacen necesario su abordaje. En el Área Sanitaria VIII de Asturias se puso en marcha en 1998 un plan de ayuda al fumador que ahora pretendemos hacer extensivo a pacientes que van a ser sometidos a cirugía programada, ya que está demostrado que el tabaco aumenta las complicaciones postoperatorias; por otra parte, afrontar una intervención quirúrgica puede ser un motivo para intentar abandonar el hábito. Actividades. Los pacientes que van a ser sometidos a intervenciones quirúrgicas serán interrogados y aconsejados durante el preoperatorio respecto el hábito tabáquico. Se les realiza el test de Richmond y si su puntuación es 7, se les deriva al centro de salud. Intervenciones. El médico de familia valora la dependencia y motivación del fumador y le ofrece tratamiento individualizado para dejar de fumar. Durante el ingreso una enfermera refuerza la cesación. Una vez de alta, se hace un seguimiento periódico en atención primaria. Evaluación. Coincidiendo con la evaluación anual de cartera de servicios se medirá el número de fumadores intervenidos quirúrgicamente que han sido aconsejados, visitados en planta, derivados y seguidos en atención primaria, así como los abstinentes al mes, 6 y 12 meses. Conclusiones. La falta de financiación del tratamiento puede ser una de las limitaciones del programa. Aunque en otros países hay experiencias de intervenciones en fumadores que van a someterse a cirugía, en nuestro medio no hemos encontrado ningún programa similar al nuestro (AU)