Graduate Seminar – Yan Ni

Date(s) - 23 Apr 2014
1:10 PM - 2:00 PM

3043 ECpE Building Addition

Title: Topological insulator thin film growth and devices

Speaker: Yan Ni, ECpE Graduate Student

Adviser: David C. Jiles, Palmer Endowed Department Chair; Anson Marston Distinguished Professor

Abstract: Topological insulators which possess a gapless surface state arising from the strong spin orbital coupling attract attentions both for fundamental science and potential applications. It was found recently, the Fermi level and Dirac cone in 3D topological insulator (Sb1-xBix)2Te3 can be tuned within the bulk band gap, leading to a charge neutrality point with high Fermi velocity and low carrier density, i.e. an ideal system for their applications. In this work, we report the successful growth of high quality (Sb1-xBix)2Te3 thin films on mica substrate by van der Waals epitaxy. The thin films with 12 nm in thickness exhibit low surface roughness of 0.7 nm in a large scale. (Sb1-xBix)2Te3 thin film with x = 0.04 shows a maxima in its sheet resistance, which indicates the achieving of the charge neutrality point in present thin films. Moreover, we found that the 2D layer-by-layer growth mode tends to break down for higher Bi concentration during growth. Our observations confirm the feasibility of depositing (Sb1-xBix)2Te3 in wide Bi range on mica substrate, which may be helpful for their application in flexible optoelectronics.

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