# Native Pb vacancy defects induced p-type characteristic in epitaxial monolayer PbSe

**Authors:** Qiwei Tian, Ping Li, Li Zhang, Yuan Tian, Long-Jing Yin, Lijie Zhang, Zhihui Qin  
**arXiv:** [2308.11931](https://arxiv.org/abs/2308.11931)  
**Date:** 2023-08-23  
**Summary page:** https://www.summarizepaper.com/en/paper/2308.11931v1/

## Key points

- Study focuses on defect-induced doping characteristics of monolayer PbSe
- Experimental and theoretical investigations conducted
- Scanning tunneling microscopy (STM) used to confirm presence of epitaxial PbSe monolayer
- Scanning tunneling spectroscopy (STS) and density functional theory (DFT) used to determine quasi-particle bandgap of PbSe (0.8eV)
- Two types of surface defects observed: vacancies of Pb atoms and replacement of absent Se atoms by Pb
- Structures of defects confirmed through theoretical optimization
- Pb vacancies move Fermi energy inside valence band and generate extra holes, resulting in p-type characteristics for PbSe
- Research provides insights into defect-induced doping behavior for future device performance based on PbSe films

## Summary

This study focuses on the defect-induced doping characteristics of monolayer PbSe, a predicted two-dimensional (2D) topological crystalline insulator (TCI). The researchers conduct experimental and theoretical investigations to understand the p-type characteristic induced by defects in epitaxial monolayer PbSe on Au(111). They begin by using scanning tunneling microscopy (STM) measurements to confirm the presence of an epitaxial PbSe monolayer with a fourfold symmetric lattice. Then, they combine scanning tunneling spectroscopy (STS) measurements with density functional theory (DFT) calculations to determine the quasi-particle bandgap of PbSe, which is found to be 0.8eV. The STM results reveal two types of surface defects: vacancies of Pb atoms and replacement of absent Se atoms by Pb. The structures of these defects are confirmed through theoretical optimization. Importantly, both STS measurements and DFT calculations provide evidence that the Pb vacancies move the Fermi energy inside the valence band and generate extra holes, resulting in p-type characteristics for PbSe. This research provides valuable insights into the defect-induced doping behavior of monolayer PbSe on Au(111), contributing to future research on device performance based on PbSe films and harnessing its thermoelectric and infrared optical properties.