Enhanced Photoinduced Carrier Generation Efficiency through Surface Band Bending in Topological Insulator Bi2Se3 Thin Films by the Oxidized Layer

Enhanced Photocharacteristics by Fermi Level Modulating in Sb2 Te3 /Bi2 Se3 Topological Insulator p-n Junction

Topological insulators have recently received attention in optoelectronic devices because of their high mobility and broadband absorption resulting from their topological surface states. In particular, theoretical and experimental studies have emerged that can improve the spin generation efficiency in a topological insulator-based p-n junction structure called a TPNJ, drawing attention in optospintronics. Recently, research on implementing the TPNJ structure is conducted; however, studies on the device characteristics of the TPNJ structure are still insufficient. In this study, the TPNJ structure is effectively implemented without intermixing by controlling the annealing temperature, and the photocharacteristics appearing in the TPNJ structure are investigated using a cross-pattern that can compare the characteristics in a single device. Enhanced photo characteristics are observed for the TPNJ structure. An optical pump Terahertz probe and a physical property measurement system are used to confirm the cause of improved photoresponsivity. Consequently, the photocharacteristics are improved owing to the change in the absorption mechanism and surface transport channel caused by the Fermi level shift in the TPNJ structure.

2D Bi2Se3 materials for optoelectronics

2D layered materials with diverse exciting properties have recently attracted tremendous interest in the scientific community. Layered topological insulator Bi2Se3 comes into the spotlight as an exotic state of quantum matter with insulating bulk states and metallic Dirac-like surface states. Its unique crystal and electronic structure offer attractive features such as broadband optical absorption, thickness-dependent surface bandgap and polarization-sensitive photoresponse, which enable 2D Bi2Se3 to be a promising candidate for optoelectronic applications. Herein, we present a comprehensive summary on the recent advances of 2D Bi2Se3 materials. The structure and inherent properties of Bi2Se3 are firstly described and its preparation approaches (i.e., solution synthesis and van der Waals epitaxy growth) are then introduced. Moreover, the optoelectronic applications of 2D Bi2Se3 materials in visible-infrared detection, terahertz detection, and opto-spintronic device are discussed in detail. Finally, the challenges and prospects in this field are expounded on the basis of current development.