물리학과 세미나 공지

일시 : 2012년 3월 14일 수요일 4 시 30분

장소 : 자연대 3114예정(추후에 공지)

내용 : Controlled growth of epitaxial oxide thin films and heterostructures by pulsed laser deposition

In the field of oxide thin films and related heterostructures, there is a widely accepted idea: If you synthesize oxide films under high vacuum condition, it is unavoidable to generate oxygen vacancies in your samples. For example, even though strontium titanate (SrTiO3) is a wide bandgap (~3.2 eV) insulator, SrTiO3 films grown in a low oxygen background pressure are prone to generate a high density oxygen vacancies, revealing metallic properties due to electron carriers donated by the oxygen vacancies. While the carrier doping resulted in fascinating behaviours, including superconductivity, the introduction of unwanted oxygen vacancies in oxide thin films has often made controversies and debates. In this presentation, we will discuss that oxygen-vacancy-free oxide film can be grown by pulsed laser deposition (PLD) even under a high vacuum condition. The amount of electron carriers can be controlled by changing dynamical properties of PLD plumes when homo-epitaxial SrTiO3 thin films are grown on SrTiO3 substrates, which result in various samples from metals even to insulators under the same growth conditions, i.e. the oxygen partial pressure, the substrate temperature, and the laser energy density. To be surprised, we can effectively modulate the dynamics of PLD plume by tuning the laser spot dimensions while keeping the same energy density. This finding suggests not only an additional degree of freedom which we can play with when synthesizing oxide films but also indispensible insight regarding PLD’s compatibility with various materials when forming heterostructures.

담당 : 정창욱 교수, 이보화교수

연사 : 켄터키 주립대학 물리학과 서성석 교수

***진로설계세미나, 신입생세미나,물리특론,물리특수를 수강하는 학생들은 학과세미나를 2번이산 참석할것

***3월19일 1시~6시까지 세미나가 있을 예정임