Abstract
Several conceptual nanodevices based on the four-atom layer alpha-and beta-Ge2Sb2 monolayers are constructed, and their electronic transport and photoelectronic properties are revealed by means of first-principles calculations. Our results demonstrate that the Ge2Sb2-based p-n junction diodes exhibit a significant rectifying effect with a high rectification ratio that can be further enhanced by increasing the doping concentration. Their p-i-n junction transistors show a field-effect behavior with a stronger rectifying effect and more substantial electronic anisot-ropy. Moreover, they also display strong photoelectronic responses in the visible light region and even among the AM1.5 spectrum, making them excellent candidates as photovoltaic materials and photoelectronic transistors. Our findings uncover the multifunctional nature of four-atom layer Ge2Sb2 monolayers, promising their exten-sive applications in future flexible semiconductor devices.