Abstract
This paper focuses on the photoelectric properties of heterostructures formed by surface-modified Si (111) and hexagonal, quintuple-layered selenides (Bi2Se3 and Sb2Te3). It was shown that H-passivated Si (111) can form robust Schottky junctions with either Bi2Se3 or Sb2Te3. When back illuminated (i.e., light incident towards the Si side of the junction), both the Bi2Se3/Si and Sb2Te3/Si junctions exhibited significant photovoltaic response at 1030 nm, which is right within the near-infrared (NIR) light wavelength range. A maximum external quantum efficiency of 14.7% with a detection response time of 2 ms for Bi2Se3/Si junction, and of 15.5% with a 0.8 ms response time for the Sb2Te3/Si junction, were achieved. Therefore, utilizing Si constituents as high-pass filters, the Bi2Se3 (Sb2Te3)/Si heterojunctions can serve as monochromatic NIR photodetectors.
Highlights
Topological insulators (TIs) possess helical surface states locked by time-reversal symmetry (TRS), and have been predicted to be promising candidates for electronic and optoelectronic device applications [1,2,3,4]
Bi2Se3 and Sb2Te3 were grown on H-passivated Si (111) via molecular beam epitaxy (MBE) and physical vapor deposition (PVD) respectively
The XRD patterns are displayed in Figure 1a; they demonstrate diffraction peaks corresponding to the (00l) planes of the Bi2Se3 and Sb2Te3
Summary
Topological insulators (TIs) possess helical surface states locked by time-reversal symmetry (TRS), and have been predicted to be promising candidates for electronic and optoelectronic device applications [1,2,3,4]. The problem of reactions between metal and silicon at the interface cannot be ignored, as it may cause poor device performance Based on these issues, we innovatively propose the use of Bi2Se3 and Sb2Te3 to construct a heterostructure with Si. The layered nature of these two materials can offer a good interfacial characteristic; the performance of the Schottky junction is likely to be further improved. The substrate of Si as a high-pass filter formed a near infrared monochromatic light detector with the Bi2Se3 and Sb2Te3 film. The external quantum efficiency and response speed of the photodetector are analyzed These results demonstrated the great potential of this TI/Si heterostructure for high-performance optoelectronic device applications
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