α-In₂Se₃ Nanostructure-Based Photodetectors for Tunable and Broadband Response

Abstract

The strong thickness-dependent narrow direct band gap of few-layer α-In2Se3 makes it a promising candidate for high-performance photodetectors. However, few researchers focus on the relationship between thickness and optoelectronic characteristics, and most results are based on the mechanically exfoliated α-In2Se3 nanoflakes. Herein, a reliable physical vapor deposition strategy to grow α-In2Se3 nanosheets with tunable thickness and submillimeter scale is reported. High-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) studies confirmed the high-quality growth of α-In2Se3 nanosheets. The back-gate field-effect transistors on SiO2 substrates display n-type semiconductor behavior. A systematical investigation of the optoelectronic properties reveals a thickness-dependent broadband response from visible (447 nm) to near-infrared (1550 nm) wavelengths with better and excellent performance obtained in thicker α-In2Se3 nanosheets than that in thinner devices. More importantly, a great improvement of the responsivity, detectivity, and external quantum efficiency (EQE) can be achieved by changing the thickness of In2Se3. The photodetector exhibits an outstanding photoresponsivity of 347.6 A/W, an ultrahigh detectivity of 1.5 × 1013 Jones, and an external quantum efficiency of 8.3 × 104%, which is superior to several α-In2Se3 nanostructure- or other two-dimensional (2D)-based photodetectors. The thickness-dependent broadband response characteristics make the α-In2Se3 nanostructure a promising candidate for multifunctional optoelectronic device applications.

Customizable Organic Charge-Transfer Cocrystals for the Dual-Mode Optoelectronics in the NIR (II) Window

“…In fact, the size effect of the height in the cocrystals cannot be ignored when considering their practical applications. Differences in height in BF X TQ cocrystals directly lead to the advantages and disadvantages exhibited by different crystals in the performance of optoelectronic devices. , Due to the size effect, as shown in the simulated 2D electric field distribution along the cross-section of the microrod (Figure S18), the cocrystals with large height exhibit light confinement in the vertical direction, and photons do not easily scatter from the upper and lower surfaces of the crystal, which is conducive to the transmission and amplification of photons inside the cocrystals. This property makes them excellent candidates for optoelectronic waveguide devices .…”