Self-Powered Bi₂Se₃/Si Position-Sensitive Detector and Its Performance Enhancement by Introducing a Si Nanopyramid Structure

Abstract

Bi2Se3, as a novel 3D topological insulator (TI), is expected to be a strong candidate for next-generation optoelectronic devices due to its intriguing optical and electrical properties. In this study, a series of Bi2Se3 films with different thicknesses of 5–40 nm were successfully prepared on planar-Si substrates and developed as self-powered light position-sensitive detectors (PSDs) by introducing lateral photovoltaic effect (LPE). It is demonstrated that the Bi2Se3/planar-Si heterojunction shows a broad-band response range of 450–1064 nm, and the LPE response is strongly dependent on the Bi2Se3 layer thickness, which can be mainly attributed to the thickness-modulated longitudinal carrier separation and transport. The 15 nm thick PSD shows the best performance with a position sensitivity of up to 89.7 mV/mm, a nonlinearity of lower than 7%, and response time as fast as 62.6/49.4 μs. Moreover, to further enhance the LPE response, a novel Bi2Se3/pyramid-Si heterojunction is built by constructing a nanopyramid structure for the Si substrate. Owing to the improvement of the light absorption capability in the heterojunction, the position sensitivity is largely boosted up to 178.9 mV/mm, which gets an increment of 199% as compared with that of the Bi2Se3/planar-Si heterojunction device. At the same time, the nonlinearity is still kept within 10% as well due to the excellent conduction property of the Bi2Se3 film. In addition, an ultrafast response speed of 173/97.4 μs is also achieved in the newly proposed PSD with excellent stability and reproducibility. This result not only demonstrates the great potential of TIs in PSD but also provides a promising approach for tuning its performance.

Boosting lateral photosensing performances in a P(VDF-TrFE)/Bi2Se3/Si heterojunction induced by surface modification and ferroelectric and pyroelectric effects

“…This performance is much greater than that achieved in other heterostructure systems. 4,12,20,27,29 Moreover, the LPV curve exhibits excellent linearity across the entire range of laser power, with the maximum nonlinearity still no more than 15%. The slight deterioration of the linearity can be ascribed to the decreased carrier diffusion length induced by the electric conductivity change in the Bi 2 Se 3 layer.…”

“…Till now, Bi 2 Se 3 -based PDs have shown excellent performance, with high responsivity, rapid response speed, and low dark current, making them ideal for use in high-speed communication, imaging, and sensing devices. 2,3,18–20 However, the narrow bandgap of Bi 2 Se 3 results in closely spaced energy levels, leading to a low interface barrier height when used in heterojunctions with other materials. To overcome this issue, different surface functionalization layers, such as polyvinylidene fluoride (PVDF), oxide dielectric materials, 21–23 have been introduced.…”

Effect of Ag layer thickness on lateral photovoltaic mechanisms in Ag/p-Si structures

“…Intensive research on the lateral photovoltaic effect (LPE) has been investigated for a long time because of its wide range of applications, especially for the precise control measurement and optical transducers [1][2][3]. Among the various structures to investigate LPE, the PN junctions and Schottky junctions are the most typical structures, which were first discovered by Schottky and Wallmark respectively [4,5].…”