39 research outputs found
Desarrollo de la comunidad de Hueytamalco Puebla MĂ©xico a travĂ©s del bambĂș como materia industrial
From Strong to Weak Coupling Regime in a Single GaN Microwire up to Room Temperature
Large bandgap semiconductor microwires constitute a very advantageous
alternative to planar microcavities in the context of room temperature strong
coupling regime between exciton and light. In this work we demonstrate that in
a GaN microwire, the strong coupling regime is achieved up to room temperature
with a large Rabi splitting of 125 meV never achieved before in a Nitride-based
photonic nanostructure. The demonstration relies on a method which doesn't
require any knowledge \'a priori on the photonic eigenmodes energy in the
microwire, i.e. the details of the microwire cross-section shape. Moreover,
using a heavily doped segment within the same microwire, we confirm
experimentally that free excitons provide the oscillator strength for this
strong coupling regime. The measured Rabi splitting to linewidth ratio of 15
matches state of the art planar Nitride-based microcavities, in spite of a much
simpler design and a less demanding fabrication process. These results show
that GaN microwires constitute a simpler and promising system to achieve
electrically pumped lasing in the strong coupling regime.Comment: 14 pages, 4 figure
Fabrication et caracterisation de nanodispositifs Ă base de nanofils de semiconducteurs III-V
Semiconductor nanowires are nanostructures with lengths up to few microns and small cross sections (10ths of nanometers). In the recent years the development in the field of III-N nanowire technology has been spectacular. In particular they are consider as promising building in nanoscale electronics and optoelectronics devices; such as photodetectors, transistors, biosensors, light source, solar cells, etc. In this work, we present fabrication and the characterization of photodetector and light emitter based devices on III-N nanowires. First we present a study of a visible blind photodetector based on p-i-n GaN nanowires ensembles grown on Si (111). We show that these devices exhibit a high responsivity exceeding that of thin film counterparts. We also demonstrate UV photodetectors based on single nanowires containing GaN/AlN multi-axial quantum discs in the intrinsic region of the nanowires. Photoluminescence and cathodoluminescence spectroscopy show spectral contributions above and below the GaN bandgap according to the variation of the discs thickness. The photocurrent spectra show a sub-band-gap peak related to the interband absorption between the confined states in the large Qdiscs. Finally we present a study of photodetectors and light emitters based on radial InGaN/GaN MQW embedded in GaN wires. The wires used as photodetectors showed a contribution below the GaN bandgap. OBIC measurements demonstrate that, this signal is exclusively generated in the InGaN MQW region. We showed that LEDs based on this structure show a electroluminescence emission and a red shift when the In content present in the QWs increases which is in good agreement with photoluminescence and cathodoluminescence results.Les nanofils semiconducteurs sont des nano-objets dont la longueur peut aller jusqu'Ă quelques microns et dont la section peut ĂȘtre infĂ©rieure Ă la dizaine de nanomĂštre. En particulier, les nanofils de nitrures d'Ă©lĂ©ments III (GaN, AlN, InN, leurs alliages ternaires et leurs hĂ©tĂ©rostructures) sont extrĂȘmement prometteurs en vue du dĂ©veloppement dâune nouvelle gĂ©nĂ©ration de dispositifs dâĂ©lectronique et dâoptoĂ©lectronique tels que photodĂ©tecteurs, nanotransistors, biocapteurs, source de lumiĂšre, cellules solaires, etc.Dans ce travail, nous prĂ©sentons la fabrication et la caractĂ©risation de deux types de dispositifs Ă base de nanofils de nitrures III-V : des photodĂ©tecteurs dâune part et des dispositifs Ă©metteurs de lumiĂšre dâautre part. Tout d'abord, nous avons rĂ©alisĂ© et caractĂ©risĂ© un photodĂ©tecteur UV aveugle Ă la lumiĂšre du jour Ă base de nanofils de GaN verticalement alignĂ©s sur un substrat de Si(111) contenant une jonction p-n. Nous avons montrĂ© que ces dispositifs prĂ©sentent une rĂ©ponse supĂ©rieure Ă celle de leurs homologues en couches minces. Ensuite, nous avons fait la dĂ©monstration de photodĂ©tecteurs UV Ă base de nanofils uniques contenant des disques quantiques GaN / AlN multi-axiales insĂ©rĂ©s dans une rĂ©gion non intentionnellement dopĂ©. Les rĂ©sultats obtenus par spectroscopie de photoluminescence (PL) et cathodoluminescence (CL) montrent des contributions spectrales en-dessous et au-dessus de la bande interdite du GaN attribuĂ©es a la variation de l'Ă©paisseur des disques. Les spectres de photocourant montrent un pic sous la bande interdite liĂ© Ă l'absorption inter-bande entre les Ă©tats confinĂ©s dans les disques les plus larges. Enfin, nous prĂ©sentons une Ă©tude de photodĂ©tecteurs et Ă©metteurs de lumiĂšre Ă base de nanofils de GaN contentant une hĂ©tĂ©rostructure cĆur-coquille InGaN / GaN. Les fils utilisĂ©s comme photodĂ©tecteurs ont montrĂ© une contribution en dessous de la bande interdite de GaN. Dâautre part, les mesures OBIC dĂ©montrent que ce signal provient exclusivement de la rĂ©gion active. Les fils de type LED basĂ©s sur la mĂȘme structure montrent une forte Ă©mission d'Ă©lectroluminescence et un dĂ©calage vers le rouge lorsque le taux dâindium prĂ©sent dans les disques quantiques augmente, en accord avec les rĂ©sultats de photoluminescence et de cathodoluminescence
Desarrollo de la comunidad de Hueytamalco Puebla MĂ©xico a travĂ©s de bambĂș como materia industrial.
Fabrication et caracterisation de nanodispositifs Ă base de nanofils de semiconducteurs III-V
Les nanofils semiconducteurs sont des nano-objets dont la longueur peut aller jusqu'Ă quelques microns et dont la section peut ĂȘtre infĂ©rieure Ă la dizaine de nanomĂštre. En particulier, les nanofils de nitrures d'Ă©lĂ©ments III (GaN, AlN, InN, leurs alliages ternaires et leurs hĂ©tĂ©rostructures) sont extrĂȘmement prometteurs en vue du dĂ©veloppement d une nouvelle gĂ©nĂ©ration de dispositifs d Ă©lectronique et d optoĂ©lectronique tels que photodĂ©tecteurs, nanotransistors, biocapteurs, source de lumiĂšre, cellules solaires, etc.Dans ce travail, nous prĂ©sentons la fabrication et la caractĂ©risation de deux types de dispositifs Ă base de nanofils de nitrures III-V : des photodĂ©tecteurs d une part et des dispositifs Ă©metteurs de lumiĂšre d autre part. Tout d'abord, nous avons rĂ©alisĂ© et caractĂ©risĂ© un photodĂ©tecteur UV aveugle Ă la lumiĂšre du jour Ă base de nanofils de GaN verticalement alignĂ©s sur un substrat de Si(111) contenant une jonction p-n. Nous avons montrĂ© que ces dispositifs prĂ©sentent une rĂ©ponse supĂ©rieure Ă celle de leurs homologues en couches minces. Ensuite, nous avons fait la dĂ©monstration de photodĂ©tecteurs UV Ă base de nanofils uniques contenant des disques quantiques GaN / AlN multi-axiales insĂ©rĂ©s dans une rĂ©gion non intentionnellement dopĂ©. Les rĂ©sultats obtenus par spectroscopie de photoluminescence (PL) et cathodoluminescence (CL) montrent des contributions spectrales en-dessous et au-dessus de la bande interdite du GaN attribuĂ©es a la variation de l'Ă©paisseur des disques. Les spectres de photocourant montrent un pic sous la bande interdite liĂ© Ă l'absorption inter-bande entre les Ă©tats confinĂ©s dans les disques les plus larges. Enfin, nous prĂ©sentons une Ă©tude de photodĂ©tecteurs et Ă©metteurs de lumiĂšre Ă base de nanofils de GaN contentant une hĂ©tĂ©rostructure cĆur-coquille InGaN / GaN. Les fils utilisĂ©s comme photodĂ©tecteurs ont montrĂ© une contribution en dessous de la bande interdite de GaN. D autre part, les mesures OBIC dĂ©montrent que ce signal provient exclusivement de la rĂ©gion active. Les fils de type LED basĂ©s sur la mĂȘme structure montrent une forte Ă©mission d'Ă©lectroluminescence et un dĂ©calage vers le rouge lorsque le taux d indium prĂ©sent dans les disques quantiques augmente, en accord avec les rĂ©sultats de photoluminescence et de cathodoluminescence.Semiconductor nanowires are nanostructures with lengths up to few microns and small cross sections (10ths of nanometers). In the recent years the development in the field of III-N nanowire technology has been spectacular. In particular they are consider as promising building in nanoscale electronics and optoelectronics devices; such as photodetectors, transistors, biosensors, light source, solar cells, etc. In this work, we present fabrication and the characterization of photodetector and light emitter based devices on III-N nanowires. First we present a study of a visible blind photodetector based on p-i-n GaN nanowires ensembles grown on Si (111). We show that these devices exhibit a high responsivity exceeding that of thin film counterparts. We also demonstrate UV photodetectors based on single nanowires containing GaN/AlN multi-axial quantum discs in the intrinsic region of the nanowires. Photoluminescence and cathodoluminescence spectroscopy show spectral contributions above and below the GaN bandgap according to the variation of the discs thickness. The photocurrent spectra show a sub-band-gap peak related to the interband absorption between the confined states in the large Qdiscs. Finally we present a study of photodetectors and light emitters based on radial InGaN/GaN MQW embedded in GaN wires. The wires used as photodetectors showed a contribution below the GaN bandgap. OBIC measurements demonstrate that, this signal is exclusively generated in the InGaN MQW region. We showed that LEDs based on this structure show a electroluminescence emission and a red shift when the In content present in the QWs increases which is in good agreement with photoluminescence and cathodoluminescence results.PARIS11-SCD-Bib. Ă©lectronique (914719901) / SudocSudocFranceF
Comparison of Three E-Beam Techniques for Electric Field Imaging and Carrier Diffusion Length Measurement on the Same Nanowires
International audienc
Modulation of Schottky Barrier Height by Nitrogen Doping and Its Influence on Responsivity of Monolayer MoS2 Photodetector
Abstract Monolayer MoS2 flakes are prepared by lowâpressure chemical vapor deposition on pâtype and nâtype silicon substrates and postâtreated under nitrogen (N2)ârich conditions to incorporate nitrogen atoms in sulfur vacancies. Ultraviolet photoelectron spectroscopy (UPS) shows an increase in work function value by 0.47 eV and 0.53 eV compared to undoped MoS2 when grown on p and nâtype substrates, respectively. Photodetection experiments conducted for doped and undoped MoS2 grown on pâtype substrate reveal a decrease in the value of photo responsivity for N2 doped MoS2 (191 A Wâ1) compared with undoped MoS2 (572 A Wâ1). Also, MoS2 crystals grown and doped on an nâtype substrate display an important enhancement of the photoresponsivity from 63 A Wâ1 for undoped to 606 A Wâ1 for N2 doped MoS2. The modulation of Schottky barrier height for N2 doped MoS2 on p type substrate decreased whereas for n type substrate the high electric field created due to the difference in the Fermi level allows for greater separation of photogenerated charge carriers. This modulation in the photoresponsivity due to the selection of the type of substrate opens up new avenues of research and engineering of atomically thin optoelectronic devices
Comparison of Three E-Beam Techniques for Electric Field Imaging and Carrier Diffusion Length Measurement on the Same Nanowires
Thermal characterization of MoS2 mono/few layers using Scanning Thermal Microscopy
International audienc