{"id":43887,"date":"2021-01-22T16:49:50","date_gmt":"2021-01-22T14:49:50","guid":{"rendered":"https:\/\/www.iemn.fr\/?p=43887"},"modified":"2021-06-24T10:11:08","modified_gmt":"2021-06-24T08:11:08","slug":"43887","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/actualites\/43887.html","title":{"rendered":"Nemanja PERIC's thesis - Density of states, band discontinuity and charge injection in one-dimensional semiconductor structures"},"content":{"rendered":"<div id='layer_slider_1'  class='avia-layerslider main_color avia-shadow  avia-builder-el-0  el_before_av_heading  avia-builder-el-first  container_wrap sidebar_right'  style='height: 261px;'  ><div id=\"layerslider_58_h5sezo4uv2hm\" data-ls-slug=\"homepageslider\" class=\"ls-wp-container fitvidsignore ls-selectable\" style=\"width:1140px;height:260px;margin:0 auto;margin-bottom: 0px;\"><div class=\"ls-slide\" data-ls=\"duration:6000;transition2d:5;\"><img loading=\"lazy\" decoding=\"async\" width=\"2600\" height=\"270\" src=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1.jpg\" class=\"ls-bg\" alt=\"\" srcset=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1.jpg 2600w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-300x31.jpg 300w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-768x80.jpg 768w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-1030x107.jpg 1030w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-1500x156.jpg 1500w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-705x73.jpg 705w\" sizes=\"auto, (max-width: 2600px) 100vw, 2600px\" \/><ls-layer style=\"font-size:14px;text-align:left;font-style:normal;text-decoration:none;text-transform:none;font-weight:700;letter-spacing:0px;border-style:solid;border-color:#000;background-position:0% 0%;background-repeat:no-repeat;width:180px;height:30px;left:0px;top:231px;line-height:32px;color:#ffffff;border-radius:6px 6px 6px 6px;padding-left:50px;background-color:rgba(0, 0, 0, 0.57);\" class=\"ls-l ls-ib-icon ls-text-layer\" data-ls=\"minfontsize:0;minmobilefontsize:0;\"><i class=\"fa fa-quote-right\" style=\"color:#ffffff;margin-right:0.8em;font-size:1em;transform:translateY( -0.125em );\"><\/i>ACTUALITES<\/ls-layer><\/div><\/div><\/div><div id='after_layer_slider_1'  class='main_color av_default_container_wrap container_wrap sidebar_right'  ><div class='container av-section-cont-open' ><div class='template-page content  av-content-small alpha units'><div class='post-entry post-entry-type-page post-entry-43887'><div class='entry-content-wrapper clearfix'>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-av_heading-f9f9e071a277c494d2fee8cb91f59077\">\n#top .av-special-heading.av-av_heading-f9f9e071a277c494d2fee8cb91f59077{\nmargin:0 0 10px 0;\npadding-bottom:4px;\n}\nbody .av-special-heading.av-av_heading-f9f9e071a277c494d2fee8cb91f59077 .av-special-heading-tag .heading-char{\nfont-size:25px;\n}\n.av-special-heading.av-av_heading-f9f9e071a277c494d2fee8cb91f59077 .av-subheading{\nfont-size:15px;\n}\n<\/style>\n<div  class='av-special-heading av-av_heading-f9f9e071a277c494d2fee8cb91f59077 av-special-heading-h2  avia-builder-el-1  el_after_av_layerslider  el_before_av_hr  avia-builder-el-first'><h2 class='av-special-heading-tag'  itemprop=\"headline\"  >Nemanja PERIC's thesis - Density of states, band discontinuity and charge injection in one-dimensional semiconductor structures<\/h2><div class=\"special-heading-border\"><div class=\"special-heading-inner-border\"><\/div><\/div><\/div>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-18u73nj-dad6a947580930e400fc42ba200e80f1\">\n#top .hr.av-18u73nj-dad6a947580930e400fc42ba200e80f1{\nmargin-top:5px;\nmargin-bottom:5px;\n}\n.hr.av-18u73nj-dad6a947580930e400fc42ba200e80f1 .hr-inner{\nwidth:100%;\n}\n<\/style>\n<div  class='hr av-18u73nj-dad6a947580930e400fc42ba200e80f1 hr-custom  avia-builder-el-2  el_after_av_heading  el_before_av_textblock  hr-left hr-icon-no'><span class='hr-inner inner-border-av-border-thin'><span class=\"hr-inner-style\"><\/span><\/span><\/div>\n<section  class='av_textblock_section av-jriy64i8-2f4600354c0449b610997916bbd9b6bc'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" >\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-13ewzjw-68e036126b913e5028f77311dc66b825\">\n.av_font_icon.av-13ewzjw-68e036126b913e5028f77311dc66b825{\ncolor:#bfbfbf;\nborder-color:#bfbfbf;\n}\n.av_font_icon.av-13ewzjw-68e036126b913e5028f77311dc66b825 .av-icon-char{\nfont-size:60px;\nline-height:60px;\n}\n<\/style>\n<span  class='av_font_icon av-13ewzjw-68e036126b913e5028f77311dc66b825 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue8c9' data-av_iconfont='entypo-fontello' ><\/span><\/span>\n<p><strong>Nemanja Peric<\/strong><\/p>\n<p>Soutenance : 27 janvier 2021 \u00e0 10h30<strong><br \/>\n<\/strong>IEMN Amphitheatre - Central Laboratory - Villeneuve d'Ascq<\/p>\n<div class=\"page\" title=\"Page 1\">\n<div class=\"layoutArea\">\n<div class=\"column\">\n<p>Acc\u00e8s \u00e0 la soutenance en distanciel : cliquer <a href=\"https:\/\/univ-lille-fr.zoom.us\/j\/91862844624pwd=USsxcncwVmphTXVGWGVNaFhTNGpaQT09\">here<\/a><\/p>\n<\/div>\n<\/div>\n<\/div>\n<h5>Jury :<\/h5>\n<p>Bassem SALEM, Laboratoire des Technologies de la Micro\u00e9lectronique, Rapporteur<\/p>\n<p>Herv\u00e9 AUBIN, Centre de Nanosciences et de Nanotechnologies, Rapporteur<\/p>\n<p>Sandrine ITHURRIA, ESPCI-ParisTech, Examinatrice<\/p>\n<p>Xavier WALLART, IEMN, Examinateur<\/p>\n<p>Louis BIADALA, IEMN Co-directeur de th\u00e8se<\/p>\n<p>Bruno GRANDIDIER, IEMN, Directeur<\/p>\n<div class=\"page\" title=\"Page 1\">\n<div class=\"layoutArea\">\n<div class=\"column\"><\/div>\n<\/div>\n<\/div>\n<\/div><\/section>\n<section  class='av_textblock_section av-jtefqx33-628129dba2299b2ecd65ebfc92eac29d'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><div  class='hr av-kjh3zw-4dff888f744b728a1aca9b3a0971493a hr-default  avia-builder-el-6  avia-builder-el-no-sibling'><span class='hr-inner'><span class=\"hr-inner-style\"><\/span><\/span><\/div>\n<h5>Summary:<\/h5>\n<p>La miniaturisation continue des composants \u00e9lectroniques a atteint un seuil au-del\u00e0 duquel les effets quantiques deviennent pr\u00e9pond\u00e9rants. Plut\u00f4t que de vouloir supprimer ces effets, il peut \u00eatre int\u00e9ressant de les mettre \u00e0 profit. Mais ce changement de perspective n\u00e9cessite d\u2019avoir une compr\u00e9hension plus fine des propri\u00e9t\u00e9s \u00e9lectroniques de nanostructures semi-conductrices consid\u00e9r\u00e9es comme de potentiels \u00e9l\u00e9ments actifs dans des dispositifs futurs. Au cours de cette th\u00e8se, deux types de structures dont la g\u00e9om\u00e9trie s\u2019apparente plus ou moins \u00e0 un syst\u00e8me uni-dimensionnel ont \u00e9t\u00e9 consid\u00e9r\u00e9s : des nanofils semi-conducteurs III-V fabriqu\u00e9s par croissance \u00e9pitaxiale en ultravide et des nanoplatelets semi-conducteurs II-VI synth\u00e9tis\u00e9s chimiquement.<\/p>\n<div class=\"page\" title=\"Page 1\">\n<div class=\"section\">\n<div class=\"layoutArea\">\n<div class=\"column\">\n<p>Dans le premier cas, l\u2019\u00e9pitaxie par jets mol\u00e9culaires s\u00e9lective de nanofils planaires compos\u00e9s d\u2019InGaAs permet d\u2019\u00e9laborer des nano-cristaux localis\u00e9s pr\u00e9cis\u00e9ment \u00e0 la surface d\u2019un substrat d\u2019InP gr\u00e2ce \u00e0 l\u2019utilisation d\u2019un masque di\u00e9lectrique. L\u2019analyse de la morphologie de ces nanofils par microscopie \u00e0 champ proche a r\u00e9v\u00e9l\u00e9 une anisotropie de forme en fonction de l\u2019orientation des nanofils. En mod\u00e9lisant la cin\u00e9tique de croissance, nous avons montr\u00e9 que cette variation de forme s\u2019explique par une diff\u00e9rence de diffusion des adatomes li\u00e9e \u00e0 la reconstruction de la surface des nanofils. Les propri\u00e9t\u00e9s de transport dans ces h\u00e9t\u00e9rostructures uni-dimensionnelles In0.53Ga0.46As\/InP ont ensuite \u00e9t\u00e9 caract\u00e9ris\u00e9es par microscopie \u00e0 effet tunnel \u00e0 pointes multiples. Deux approches exp\u00e9rimentales bas\u00e9es l\u2019une sur la spectroscopie tunnel \u00e0 deux contacts, l\u2019autre sur des mesures \u00e0 quatre pointes en contact ont \u00e9t\u00e9 con\u00e7ues pour remonter \u00e0 la mesure des discontinuit\u00e9s de bande entre le substrat d\u2019InP et les nanofils d\u2019InGaAs. L\u2019obtention des discontinuit\u00e9s de bande est directe et ne requiert ni fabrication d\u2019\u00e9lectrodes, ni mod\u00e9lisation des caract\u00e9ristiques I(V), contrairement aux techniques \u00e9lectriques conventionnelles.<\/p>\n<\/div>\n<\/div>\n<div class=\"layoutArea\">\n<div class=\"column\">\n<p>Dans un second temps, des nanoplaquettes de CdSe ont \u00e9t\u00e9 \u00e9tudi\u00e9es. Elles s\u2019apparentent \u00e0 des puits quantiques collo\u00efdaux d\u2019\u00e9paisseur limit\u00e9e \u00e0 quelques plans atomiques pour des dimensions lat\u00e9rales comprises entre plusieurs nanom\u00e8tres et quelques dizaines de nanom\u00e8tres. Bien que leurs propri\u00e9t\u00e9s excitoniques aient fait l\u2019objet de nombreuses \u00e9tudes, le r\u00f4le du confinement quantique lat\u00e9ral sur la localisation des porteurs de charge est encore mal connu. La spectroscopie \u00e0 effet tunnel a \u00e9t\u00e9 utilis\u00e9e paquet pour d\u00e9terminer la densit\u00e9 d\u2019\u00e9tats en bande de conduction de nanoplaquettes individuelles et de nanoplaquettes assembl\u00e9es en paquet. Les mesures ont montr\u00e9 l\u2019existence, d\u2019une part, de singularit\u00e9s superpos\u00e9es \u00e0 une oscillation de la densit\u00e9 d\u2019\u00e9tats, en bon accord avec la densit\u00e9 d\u2019\u00e9tats calcul\u00e9e par la m\u00e9thode des liaisons fortes et, d\u2019autre part, la pr\u00e9sence de pi\u00e8ge sur les parois lat\u00e9rales des plaquettes. Contrairement \u00e0 l\u2019exciton dont le confinement est plus important, la d\u00e9localisation de l\u2019\u00e9lectron est fortement influenc\u00e9e par le confinement lat\u00e9ral et la pr\u00e9sence de pi\u00e8ge. En tirant parti de cette d\u00e9couverte, des travaux pr\u00e9liminaires par spectroscopie optique de nanoplaquettes c\u0153ur-coquille permettent d\u2019entrevoir l\u2019int\u00e9r\u00eat d\u2019une couronne pour mieux contr\u00f4ler le confinement des porteurs de charge dans ces objets.<\/p>\n<h5>Abstract:<\/h5>\n<p>The traditional transistor miniaturization is resulting in devices experiencing quantum effects. Rather than fighting these effect by developing new architectures of conventional silicon-based devices, the long-term solution might be in revisiting existing knowledge of these fundamental concepts and studying them in a well-controlled and methodological manner. Consequently, the newly emergent insights could be applied to the keystones of modern-day electronic devices, such as one-dimensional shape and the presence of heterointerface, but on different materials. This, in fact, has a potential to yield an alternative approach to information processing and computation.<\/p>\n<p>Nowadays, it is possible to obtain nanostructures of any shape and size due to recent breakthroughs in nanofabrication. This thesis aims to exploit such possibilities to simulate an experimental environment in which quantum confinement effect can be studied in a controlled manner on different one-dimensional semiconductor nano-heterostructures. At first, a reliable methodology will be developed to accurately determine the band alignment between two dissimilar semiconductors comprising a heterointerface. This will be achieved on planar one-dimensional InGaAs nanostructures grown on InP by selective area molecular beam epitaxy, a nanofabrication method which, to date, offers the best control of nanostructure shape, size, position, and orientation in ultrahigh vacuum. The surface reconstruction, as well as the entire structure morphology will be investigated in great detail by means of atomic force microscopy and scanning tunneling microscopy, while the aforementioned growth will be described by modeling the diffusion dynamics. A combination of low-temperature two-probe scanning tunneling spectroscopy and room-temperature four-probe contact measurements will be utilized to obtain accurate information about the band alignment and charge transport of the heterosystem.<\/p>\n<p>Once proven successful, the approach will be employed to study nanostructures of much smaller dimensions, where quantum size effect is ever-present: colloidal CdSe nanoplatelets, which imitate the typical optical characteristics of epitaxial quantum wells, but, due to anisotropic lateral dimensions, make the understanding of the impact of finite lateral confinement on the behavior of the free charge carriers more complex. In addition to the study of the morphology of the nanoplatelets and of their optical transitions, low-temperature scanning tunneling microscopy and spectroscopy investigations will be performed. Once drop-casted onto the gold substrate, the density of states of the nanoplatelets will be directly probed in order to accurately determine the extent of quantum confinement experienced by the carriers as a function of the nanoplatelets thickness, temperature and spatial configuration. The results which are, on one hand, inconsistent with foregoing quantum well-like perception found in literature, while on the other, perfectly in line with our tight binding calculations, will establish a solid baseline for the follow-up study CdSe\/CdS core-crown nanoplatelets.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"page\" title=\"Page 1\">\n<div class=\"section\">\n<div class=\"layoutArea\">\n<div class=\"column\"><\/div>\n<\/div>\n<div class=\"layoutArea\">\n<div class=\"column\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/section>","protected":false},"excerpt":{"rendered":"","protected":false},"author":2,"featured_media":43892,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[],"class_list":["post-43887","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-actualites"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/43887","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/comments?post=43887"}],"version-history":[{"count":0,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/43887\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media\/43892"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=43887"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=43887"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=43887"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}