High Performance n- and p-Type Field-Effect Transistors Based on Hybridly Surface-Passivated Colloidal PbS Nanosheets

TL;DR

This paper demonstrates high-performance colloidal PbS nanosheet transistors with tunable n- and p-type behavior, achieved through surface passivation, contact metal modification, and environmental exposure, advancing colloidal materials for future electronics.

Contribution

It introduces a method to enhance and control the electronic properties of colloidal PbS nanosheets, including achieving high mobility and on/off ratios, through surface and environmental modifications.

Findings

Halide ion passivation improves conductivity and mobility.

Achieved n-type behavior with mobility of 248 cm^2V^-1s^-1.

Conductivity can be switched from n-type to p-type by changing contact metal and environment.

Abstract

Colloidally synthesized nanomaterials are among the promising candidates for future electronic devices due to their simplicity and the inexpensiveness of their production. Specifically, colloidal nanosheets are of great interest since they are conveniently producible through the colloidal approach while having the advantages of two-dimensionality. In order to employ these materials, according transistor behavior should be adjustable and of high performance. We show that the transistor performance of colloidal lead sulfide nanosheets is tunable by altering the surface passivation, the contact metal, or by exposing them to air. We found that adding halide ions to the synthesis leads to an improvement of the conductivity, the field-effect mobility, and the on/off ratio of these transistors by passivating their surface defects. Superior n-type behavior with a field-effect mobility of 248 cm^2V^-1s^-1 and an on/off ratio of 4x10^6 is achieved. The conductivity of these stripes can be changed from n-type to p-type by altering the contact metal and by adding oxygen to the working environment. As a possible solution for the post-Moore era, realizing new high quality semiconductors such as colloidal materials is crucial. In this respect, our results can provide new insights which helps to accelerate their optimization for potential applications.