Selective Patterning of Bi2Te3 Nanoplatelets Via Microcontact Printing

Bismuth Telluride (Bi₂Te₃) and its family chalcogenides are recently confirmed as topological insulators. Their electrical transport is dissipationless, which will have an impact on future applications, including thermoelectrics, electronics, and IR detectors. One of the critical challenges is to selectively assemble two-dimensional Bi₂Te₃ nanosheets on a variety of substrates. In this work, the chemistry of selectively patterning Bi₂Te₃  nanoplatelets on silicon substrates using micro contact printing (μCP) technique is investigated. Masters of three μCP stamps (patterns of letter A, houndstooth and square array, respectively) were made using regular photolithography processes, and μCP stamps were fabricated by pouring polydimethylsiloxane (PDMS) on the master and curing PDMS at a temperature of 65⁰C for 3 hrs. μCP processes were applied to print 3-Aminopropyltrimethoxysilane (APTMS) with the three designed patterns onto silicon substrates, and Bi₂Te₃ nanoplatelets, grown via a solvo-thermal process, were coated selectively. The results indicate that Bi₂Te₃ nanoplatelets are immobilized on the APTMS printed regions. It is suspected that an electrostatic interaction between positively-charged amine groups and negatively-charged Bi₂Te₃ nanoplatelets is the driving force of the selective patterning. We have demonstrated that μCP is a controllable, facile process for assembling two-dimensional Bi₂Te₃ nanosheets and other chalcogenides.