{"id":76665,"date":"2025-12-22T11:55:31","date_gmt":"2025-12-22T09:55:31","guid":{"rendered":"https:\/\/www.iemn.fr\/?p=76665"},"modified":"2026-01-29T09:59:29","modified_gmt":"2026-01-29T07:59:29","slug":"corentin-sthioul-these","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/a-la-une\/corentin-sthioul-these.html","title":{"rendered":"Corentin Sthioul  11\/12\/2025 &#8211; \u00ab\u00c9pitaxie de van der Waals d\u2019h\u00e9terostructures \u00e0 base de TaSe2 et HfSe2 sur substrats semiconducteurs\u00bb"},"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_102y2grv3z1ul\" 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-76665'><div class='entry-content-wrapper clearfix'>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-mih9a83v-6e9f65cfb8776e3a389cb06a9f21bcbd\">\n#top .av-special-heading.av-mih9a83v-6e9f65cfb8776e3a389cb06a9f21bcbd{\nmargin:0 0 10px 0;\npadding-bottom:4px;\ncolor:#e58302;\n}\nbody .av-special-heading.av-mih9a83v-6e9f65cfb8776e3a389cb06a9f21bcbd .av-special-heading-tag .heading-char{\nfont-size:25px;\n}\n.av-special-heading.av-mih9a83v-6e9f65cfb8776e3a389cb06a9f21bcbd .special-heading-inner-border{\nborder-color:#e58302;\n}\n.av-special-heading.av-mih9a83v-6e9f65cfb8776e3a389cb06a9f21bcbd .av-subheading{\nfont-size:15px;\n}\n<\/style>\n<div  class='av-special-heading av-mih9a83v-6e9f65cfb8776e3a389cb06a9f21bcbd av-special-heading-h2 custom-color-heading  avia-builder-el-1  el_after_av_layerslider  el_before_av_hr  avia-builder-el-first  av-linked-heading'><h2 class='av-special-heading-tag'  itemprop=\"headline\"  >Corentin Sthioul 11\/12\/2025 &#8211; \u00ab\u00c9pitaxie de van der Waals d\u2019h\u00e9terostructures \u00e0 base de TaSe2 et HfSe2 sur substrats semiconducteurs\u00bb<\/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-fd5f2e9d63bf552d6910d12f255eb26e'   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-649e41ac67c26b53aa0b3d91d18e5f5a\">\n.av_font_icon.av-13ewzjw-649e41ac67c26b53aa0b3d91d18e5f5a{\ncolor:#e58302;\nborder-color:#e58302;\n}\n.av_font_icon.av-13ewzjw-649e41ac67c26b53aa0b3d91d18e5f5a .av-icon-char{\nfont-size:60px;\nline-height:60px;\n}\n<\/style>\n<span  class='av_font_icon av-13ewzjw-649e41ac67c26b53aa0b3d91d18e5f5a 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<h4>Corentin Sthioul<\/h4>\n<p><strong>Le 11 d\u00e9cembre 2025 \u00e0 10h00<br \/>\n<\/strong>Amphith\u00e9\u00e2tre LCI<\/p>\n<\/div><\/section>\n<section  class='av_textblock_section av-jtefqx33-26fa44c544b10063385818eda37e027b'   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><strong><span style=\"color: #800000;\">Jury :<\/span><\/strong><\/h5>\n<ul>\n<li>Rapporteuse: Marie-Paule Besland, Directeur de recherche au CNRS \u2013 IMN<\/li>\n<li>Rapporteur Joao Marcelo Jordao Lopes, Senior scientist au PDI<\/li>\n<li>Examinateur Mohamed Al Khalfioui, Ma\u00eetre de conf\u00e9rences \u00e0 l\u2019Universit\u00e9 C\u00f4te d\u2019Azur \u2013 CRHEA<\/li>\n<li>Examinateur Matthieu Jamet, Directeur de recherche au CEA \u2013 Spintec<\/li>\n<li>Examinateur Aldelkarim Ouerghi, Directeur de recherche au CNRS \u2013 C2N<\/li>\n<li>Examinatrice Pascale Diener, Enseignante-chercheuse \u00e0 JUNIA \u2013 IEMN<\/li>\n<li>Directeur de th\u00e8se :Xavier Wallart, Directeur de recherche au CNRS \u2013 IEMN<\/li>\n<\/ul>\n<h5><span style=\"color: #800000;\">Summary:<\/span><\/h5>\n<div class=\"elementToProof\">\n<div>\u00ab\u00a0Les dichalcog\u00e9nures de m\u00e9taux de transition (TMDC) ont suscit\u00e9 un int\u00e9r\u00eat consid\u00e9rable au cours des deux derni\u00e8res d\u00e9cennies en raison de la grande vari\u00e9t\u00e9 de propri\u00e9t\u00e9s qu\u2019ils offrent, ainsi que de la capacit\u00e9 unique des mat\u00e9riaux bidimensionnels (2D) \u00e0 pouvoir \u00eatre isol\u00e9s en couches atomiquement minces ou int\u00e9gr\u00e9s dans des h\u00e9t\u00e9rostructures complexes, quel que soit le d\u00e9saccord de maille. Cependant, le manque de techniques de fabrication \u00e0 grande \u00e9chelle a frein\u00e9 leur emploi pour des applications pratiques. Notamment, si l\u2019\u00e9pitaxie par jets mol\u00e9culaires (MBE) est une technique permettant de produire des semi-conducteurs de haute qualit\u00e9, le faible couplage entre les couches 2D repr\u00e9sente un d\u00e9fi majeur pour la croissance \u00e9pitaxiale, car il favorise le d\u00e9salignement dans le plan et la formation de macles. Le choix d\u2019un substrat appropri\u00e9 est donc une question importante, mais toujours ouverte.<\/div>\n<div>Dans cette th\u00e8se, la MBE est utilis\u00e9e pour faire cro\u00eetre du TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> sur des substrats de GaP(111)B et GaAs(111)B, et du HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> sur des substrats de GaP(111)B et Si(111). Ces substrats semi-conducteurs tridimensionnels (3D) sont disponibles commercialement, mais leur surface doit \u00eatre passiv\u00e9e avant lacroissance de mat\u00e9riaux 2D. Ceci a \u00e9t\u00e9 r\u00e9alis\u00e9 par un recuit sous flux de Se pour GaP et GaAs, tandis qu\u2019une croissance autolimit\u00e9e de GaSe a permis le d\u00e9p\u00f4t d\u2019une demi-monocouche de GaSe sur Si. Dans chaque cas, une fois les propri\u00e9t\u00e9s \u00e9lectroniques et la morphologie de la surface obtenue enti\u00e8rement caract\u00e9ris\u00e9es, l\u2019influence des param\u00e8tres de croissance lors de l\u2019\u00e9pitaxie de TMDC est discut\u00e9e. L\u2019\u00e9tude d\u2019un TMDC m\u00e9tallique (TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>) et d\u2019un semi-conducteur (HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>) offre enfin la possibilit\u00e9 de d\u00e9velopper une h\u00e9t\u00e9rostructure m\u00e9tal\/semi-conducteur 2D.<\/div>\n<div><\/div>\n<div>Dans les monocouches de TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>, la phase\u00a0 isolante de Mott 1T ou la phase m\u00e9tallique 1H peuvent \u00eatre s\u00e9lectivement fabriqu\u00e9es \u00e0 haute ou basse temp\u00e9rature du substrat, respectivement. En revanche, les polytypes H, plus stables, sont favoris\u00e9s en multicouches, pour lesquelles l\u2019alignement rotationnel et la cristallinit\u00e9 s\u2019am\u00e9liorent en augmentant la temp\u00e9rature de croissance. Cependant, une morphologie plus rugueuse est observ\u00e9e autour de 400\u2013500 \u00b0C, tandis qu\u2019\u00e0 plus haute temp\u00e9rature, une d\u00e9ficience en Se est \u00e9v\u00e9l\u00e9e dans les multicouches de TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>accompagn\u00e9e d\u2019une interdiffusion avec le substrat GaP. Cependant, ce substrat semble plus adapt\u00e9 que GaAs, qui souffre d\u2019une importante incorporation de Se lors de la croissance de TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>. Les monocouches 1T-TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> pr\u00e9sentent un moir\u00e9 induit par la diff\u00e9rence de param\u00e8tre de maille par rapport \u00e0 GaP, en plus de l\u2019onde de densit\u00e9 de charge en \u221a13\u00d7\u221a13 attendue pour ce mat\u00e9riau et de la phase isolante de Mott stable \u00e0 temp\u00e9rature ambiante, contrastant avec la conductivit\u00e9 m\u00e9tallique des phases H.<br \/>\nEn revanche, HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> pr\u00e9par\u00e9 sur GaP ne forme que la phase 1T, et sa cristallinit\u00e9 est presque ind\u00e9pendante des conditions de croissance, mais d\u00e9pend plut\u00f4t de la temp\u00e9rature de recuit. L\u2019\u00e9paisseur joue \u00e9galement un r\u00f4le important, le faible d\u00e9saccord de maille avec GaP induisant une l\u00e9g\u00e8re contrainte dans les couches minces qui se rel\u00e2che avec l\u2019\u00e9paisseur. Sur substrats de silicium, cependant, HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> souffre de l\u2019instabilit\u00e9 de la demi-monocouche de GaSe et de la formation d\u2019une phase interm\u00e9diaire de SiSe<span class=\"Uni\" title=\"U+2093 indice lettre latine minuscule x\"><sub>x<\/sub><\/span>. La caract\u00e9risation \u00e9lectronique sugg\u00e8re un dopage de type N dans les couches minces de HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>, qui est r\u00e9duit dans les couches plus \u00e9paisses, conduisant \u00e0 une r\u00e9sistivit\u00e9 \u00e9lev\u00e9e. Ce dopage N est largement pr\u00e9serv\u00e9 dans les h\u00e9t\u00e9rostructures TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>\/HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>, bien que ces derni\u00e8res subissent une importante interdiffusion \u00e0 l\u2019interface.\u00a0\u00bb<\/div>\n<div><\/div>\n<\/div>\n<p>Abstract:<\/p>\n<div class=\"elementToProof\">\n<div>\u00ab\u00a0Layered transition metal dichalcogenides (TMDCs) have attracted a significant attention in the last two decades owing to the large variety of properties they offer together with the unique ability of two-dimensional (2D) materials to be isolated in atomically thin layers or integrated in complex heterostructures regardless of the lattice mismatch. However, the lack of scalable fabrication techniques has hindered their use in practical applications. Especially, if molecular beam epitaxy (MBE) is a technique capable of growing high-quality semiconductors, the weak coupling between 2D layers represents a serious challenge for epitaxial growth because it favors rotational misalignment and twin formation. This makes the choice of an appropriate substrate an important and yet open question.<br \/>\nIn this thesis, MBE is employed to grow TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> on GaP(111)B and GaAs(111)B substrates and HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> on GaP(111)B and Si(111). These semiconducting three-dimensional (3D) substrates are commercially available, but they require a passivation of their surface prior to 2D material growth. This has been achieved through an annealing under a Se flux for GaP and GaAs, whereas a self-limiting GaSe growth has allowed the deposition on a GaSe half-monolayer on Si. In each case, once the electronic properties and the morphology of the resulting surface has been fully characterized, the influence of the growth parameters during TMDC epitaxy is discussed. The focus on a metallic TMDC (TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>) and a semiconducting one (HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>) finally offers the opportunity to grow a 2D metal\/semiconductor heterostructure.In TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> monolayers, Mott insulating 1T or metallic 1H phase can be selectively grown at high or low substrate temperature, respectively. On the other hand, the stable H polytypes are favored in fewlayers, for which the rotational alignment and crystallinity improve with increasing growth temperature. However, a rougher morphology is observed around 400\u2013500 \u00b0C, whereas at higher temperature, a Se-deficiency is revealed in the TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> few-layers accompanied by an interdiffusion with the GaP substrate. Still, this substrate appears more suited than GaAs, which suffers from a large Se incorporation during TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> growth. The 1T-TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> monolayers reveal a moir\u00e9 induced by the different GaP lattice parameter, in addition to the expected \u221a13\u00d7\u221a13 charge density wave and Mott insulating phase stable at room temperature, contrasting with the metallic conductivity of H phases. By contrast, HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> grown on GaP exhibits only the 1T phase, and its crystallinity is almost independent of the growth conditions, but rather depends on the annealing temperature. The thickness also plays an important role, the small lattice mismatch with GaP inducing a slight strain in thin layers which is relaxed with thickness. On Si substrates, however, HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span> suffers from the instability of the GaSe half-monolayer and the formation of an intermediate SiSe<span class=\"Uni\" title=\"U+2093 indice lettre latine minuscule x\"><sub>x<\/sub><\/span> phase. Electronic characterization suggests a n-type doping in thin HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>layers which is reduced in thicker films, leading to a high resistivity. This n-type character is largely preserved in the TaSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>\/HfSe<span class=\"Uni\" title=\"U+2082 (\u00a0X\u2082\u00a0)\">\u2082<\/span>heterostructures although the latter suffer from a significant intermixing at the interface.\u00a0\u00bb<\/div>\n<\/div>\n<\/div><\/section>","protected":false},"excerpt":{"rendered":"","protected":false},"author":20,"featured_media":71083,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,8,199],"tags":[],"class_list":["post-76665","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-a-la-une","category-actualites","category-these"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/76665","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\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/comments?post=76665"}],"version-history":[{"count":7,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/76665\/revisions"}],"predecessor-version":[{"id":76968,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/76665\/revisions\/76968"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media\/71083"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=76665"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=76665"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=76665"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}