Organic rubrene/topological insulator Bi₂Se₃/SiO₂ hybrid heterojunction photodetectors for broadband and ultrafast photodetection application

Abstract

Organic-inorganic heterostructures (OIHs) are an emerging topic that has attracted great research enthusiasm due to their unique features for electronic and optoelectronic applications. Although OIHs constructed with topological insulators and...

Epitaxial Topological Insulator Bi2Te3 for Fast Visible to Mid-Infrared Heterojunction Photodetector by Graphene As Charge Collection Medium

“…We fitted the dependence of photocurrent on power density piecewise at 0 V on the basis of the formula of I ph = AP Θ , in which the obtained Θ 2 (Θ 1 ) is about 0.11 (0.94) at a high (low) power density range (Figure S5c, Supporting Information). The relatively small of Θ 2 may be caused by light absorption saturation of the Bi 2 Te 3 layer since the light absorption of GaAs is forbidden at a wavelength of 1550 nm. , From photocurrent distribution mapping at a visible–near-infrared range of 405–1550 nm in Figure c, the most sensitive photodetection waveband is around near-infrared of 785 nm, which is consistent with the absorption spectrum of the Bi 2 Te 3 /GaAs heterostructure. To study the mid-infrared photoresponse properties of Gr/Bi 2 Te 3 /GaAs heterojunction PD, the photocurrent curves from 2.25 to 4.5 μm were directly collected by a semiconductor parameter analyzer at room temperature.…”

“…Under light illumination with a photon energy larger than the bandgap (∼1.42 eV) of GaAs, both the Bi 2 Te 3 layer and GaAs substrate would absorb incident photons, casing the generation of photogenerated electron–hole pairs in the vis–NIR regions. However, when the photon energy is below the bandgap of GaAs, the incident light would be mainly absorbed by the Bi 2 Te 3 IT layer (its bulk bandgap is ∼0.15 eV), which can effectively convert photons to electron–hole pairs by stimulating electron transition from the bulk valence band (BVB) to the empty bulk conduction band (BCB) or unoccupied surface-states (SS) over the wide spectral range from visible to mid-infrared waveband . Subsequently, the photogenerated electron–hole pairs would be separated and transferred by the action of the built-in electric field at the heterointerface of Bi 2 Te 3 /GaAs, in which the electrons would inject into the GaAs substrate whereas the holes in Bi 2 Te 3 layer would be collected by graphene and therefore lead to the photocurrent in an external circuit.…”

“…To date, most of the reported TIs-based PDs are mainly fabricated with Bi 2 Se 3 , Bi 2 Te 3 , and Sb 2 Te 3 , in which constructing the heterojunction of these materials is very popular because they can effectively improve the signal-to-noise ratio. − However, the materials used in TIs-based PDs are primary focused on nanoplate or nanosheet grown by solvothermal or chemical vapor deposition approach currently. , These preparation methods make it hard to meet the needs of large-scale array device application due to the uncontrollable material sizes or layer numbers. In comparison, the controllable and high-quality TIs thin film is more suitable to be obtained by using efficient pulsed laser deposition (PLD), metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), etc . − Noteworthy, the selection of an appropriate substrate or buffer layer is critical to epitaxial growth of a high-quality film. − Recently, Dycus et al reported an attractive solution for direct epitaxial growth of Bi 2 Te 3 TI film on a gallium arsenide (GaAs) substrate, demonstrating the importance of a formed Ga 2 Te 3 template between the GaAs/Bi 2 Te 3 interface .…”

Ultrasensitive and Self‐Powered SnSe/Ge Heterojunction Photodetector Driven by Spontaneously Interfacial Excitation Transfer of Carriers

“…It may make the large number of photoexcitons originating from band-gap internal photoemission easy to survive in optoelectronic devices. [22,31] The controlled growth of 2D layered SnSe film with high-quality can minimize the defect density, and facilitate to reduce the grain boundary recombination of photoexcited carriers. However, the photoelectric conversion efficiency from the pure SnSe film in optoelectronic devices is still lower, due to the limited transfer efficiency of carriers.…”

“…[14][15][16][17][18] Consequently, benefiting from the existence of Dirac surface state on TCI phase SnSe crystal, it is advantageous to realize the predominated transport of surface carriers with no backscattering and higher mobility. [19][20][21][22] Whereas, for the SnSe crystal with orthorhombic lattice structure, it is favorable for the layer-by-layer growth pattern. This can help to create SnSerelated heterojunctions with sharp interfaces.…”