A plausible method of preparing the ideal p-n junction interface of a thermoelectric material by surface doping

TL;DR

This paper demonstrates a surface doping method using Ta adsorption on 2D SnSe to create an atomically sharp p-n junction interface, promising enhanced thermoelectric device performance.

Contribution

It introduces a simple surface treatment technique to form a well-defined p-n interface in 2D materials, advancing thermoelectric device fabrication.

Findings

Ta adsorption shifts valence band, inducing surface n-type behavior.

Surface doping creates an atomically thin n-region on p-doped SnSe.

The method enables high-quality p-n junction interfaces in 2D materials.

Abstract

Recent advances in two-dimensional (2D) crystals make it possible to realize an ideal interface structure that is required for device applications. Specifically, a p-n junction made of 2D crystals is predicted to exhibit an atomically well-defined interface that will lead to high device performance. Using angle-resolved photoemission spectroscopy, a simple surface treatment was shown to allow the possible formation of such an interface. Ta adsorption on the surface of a p-doped SnSe shifts the valence band maximum towards higher binding energy due to the charge transfer from Ta to SnSe that is highly localized at the surface due to the layered structure of SnSe. As a result, the charge carriers of the surface are changed from holes of its bulk characteristics to electrons, while the bulk remains as a p-type semiconductor. This observation suggests that the well-defined interface of a p-n junction with an atomically thin {\it n}-region is formed between Ta-adsorbed surface and bulk.