Fabrication of nanocrystal superlattice microchannels by soft-lithography for electronic measurements of single crystalline domains

TL;DR

This paper introduces a high-throughput method using microcontact printing to create nanocrystal superlattice microchannels, enabling detailed electronic measurements of single-crystalline domains with improved charge transport efficiency.

Contribution

The study presents a novel, scalable fabrication technique for superlattice microchannels that facilitates statistical analysis of charge transport in single-crystalline nanocrystal domains.

Findings

Microchannels of ~4 μm² were successfully fabricated.

Charge transport in microchannels is significantly more efficient.

Up to 330 microchannels per device enable statistical studies.

Abstract

We report a high-throughput and easy-to-implement approach to fabricate microchannels of nanocrystal superlattices with dimensions of ~4 micrometer^2, thus approaching the size of typical single-crystalline domains. By means of microcontact printing, highly ordered superlattices with microscale dimensions are transferred onto photolithographically prepatterned microelectrodes, obtaining well-defined superlattice microchannels. We present step-by-step guidelines for microfabrication, nanocrystal self-assembly and patterning to archive large quantities of up to 330 microchannels per device for statistically meaningful investigations of charge transport in single-crystalline superlattice domains. As proof-of-concept, we perform conductivity and field-effect transistor measurements on microchannels of PbS nanocrystal superlattices. We find that the electric transport within microchannel superlattices is orders of magnitude more efficient than within conventional large-scale channels, highlighting the advantage of the near single-crystalline microchannels presented in this paper.