{"id":16970,"date":"2018-05-07T09:45:08","date_gmt":"2018-05-07T07:45:08","guid":{"rendered":"https:\/\/www.iemn.fr?p=16970"},"modified":"2019-09-06T10:38:21","modified_gmt":"2019-09-06T08:38:21","slug":"these-semi-conducteurs","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/actualites\/these-semi-conducteurs.html","title":{"rendered":"Thesis: Study of non-stoichiometric III-V semiconductors for sampling microwave signals"},"content":{"rendered":"

\"\"<\/a>Thomas Demonchaux<\/strong>
\nThesis defence<\/span><\/p>\n

16 May 2018 at 10:30 a.m.
\nIEMN Amphitheatre - Villeneuve d'Ascq<\/strong>
\n<\/em><\/p><\/blockquote>\n

Abstract:<\/strong><\/p>\n

Discovered in the late 1980s, low-temperature epitaxial gallium arsenide (GaAs-BT) has interesting properties for optoelectronic applications. Its properties are closely linked to the presence of point defects, the deep levels of which give lifetimes compatible with its use as an active layer in photo-switches. With the aim of improving current knowledge of the physical origin of the lifetime and thus optimising it, this thesis work involved carrying out an in-depth study of the material, in particular by combining macroscopic analyses with microscopic characterisation. It is divided into five chapters, the first of which presents the current state of knowledge of GaAs-BT, while the second describes the various techniques used in this study. The third chapter looks at the chemical composition of the low-temperature epitaxial layer and its structural characterisation by X-ray diffractometry. It reveals the growth of ternary or quaternary compounds highly diluted in phosphorus and indium and suggests the presence of V-element antisites. The presence of phosphorus raises the question of the chemical nature of these antisites. The next chapter aims to identify the point defects embedded in the material using low-temperature scanning tunneling microscopy. Although the majority of the defects differ from the antisites observed in the literature by having a negative charge state and a changing appearance when the tip passes through, an analysis of the imaging conditions as a function of temperature combined with ab-initio calculations indicates the preferential formation of arsenic antisites compared with phosphorus antisites. The final chapter is devoted to the characterisation of the material after annealing. The particularity of this section lies in the discovery that the antisites do not precipitate at a growth temperature of 325\u00b0C and therefore give the most interesting lifetimes for the desired applications.<\/p>\n

Jury members :<\/strong><\/p>\n\n\n\n
Mr Alain Le Corre
\nMr Georges Bremond
\nMr Didier Sti\u00e9venard
\nMr St\u00e9phane Formont
\nMr Bruno Grandidier
\nMr Xavier Wallart<\/td>\n		Professor, INSA Rennes
\nProfessor, INSA Lyon
\nDirector of Research, CNRS, IEMN
\nEngineer, Thal\u00e8s
\nDirector of Research, CNRS, IEMN
\nDirector of Research, CNRS, IEMN<\/td>\n		Rapporteur
\nRapporteur
\nMember
\nMember
\nDirector
\nCo-director<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>","protected":false},"excerpt":{"rendered":"

Thomas Demonchaux Soutenance de th\u00e8se Le 16 mai 2018 \u00e0 10h30 IEMN Amphith\u00e9\u00e2tre – Villeneuve d’Ascq Abstract : D\u00e9couvert \u00e0 la fin des ann\u00e9es 80, l\u2019ars\u00e9niure de gallium \u00e9pitaxi\u00e9 \u00e0 basse temp\u00e9rature (GaAs-BT) pr\u00e9sente des propri\u00e9t\u00e9s int\u00e9ressantes pour des applications opto-\u00e9lectroniques. Ses propri\u00e9t\u00e9s sont intimement li\u00e9es \u00e0 la pr\u00e9sence de d\u00e9fauts ponctuels, dont les niveaux […]<\/p>\n","protected":false},"author":2,"featured_media":16971,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_members_access_role":[],"_members_access_error":""},"categories":[8],"tags":[124,126,125],"class_list":["post-16970","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-actualites","tag-hyperfrequences","tag-non-stoechiometriques","tag-semi-conducteurs"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/16970","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=16970"}],"version-history":[{"count":0,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/16970\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media\/16971"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=16970"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=16970"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=16970"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}