Photodetector Arrays Based on MBE‐Grown GaSe/Graphene Heterostructure

Abstract

mechanical strength, flexibility, and chemical stability. [1][2][3] However, the absence of a bandgap in graphene has limited its application in optoelectronics. [4] This has introduced a passive way of using graphene by integrating it with other functional materials. [5,6] Integration of graphene with 1D or 2D materials, such as inorganic semiconductors, [7,8] chalcogenides, [9][10][11] and hexagonal boron nitride (h-BN), [12][13][14] has created interesting and tunable optoelectronic properties suitable for multifunctional device applications. Particularly, 2D materials such as GaSe, InSe, and MoS 2 can be stacked or grown on graphene supported by the van der Walls (vdW) forces. [9,[15][16][17][18][19][20] GaSe is a 2D vdW chalcogenide semiconductor material with a direct bandgap of 2.1 eV in its bulk form. A single layer of GaSe possesses a larger and indirect bandgap (3.0 eV), which turns into a smaller and direct bandgap (2.1 eV) material upon increasing the number of vdW layers. [21,22] It makes the bulk GaSe a suitable material for photodetection and photovoltaic applications. Exfoliated GaSe flakes have been demonstrated for photodetector application with a responsivity of 2.8 A W -1 for 254 nm light. [21] Recently, photodetectors based on GaSe and graphene heterostructures have also been studied for various optical ranges. [23,15] Researchers have demonstrated graphene as an electrode in two terminals or gated photo detector devices. [16,21] Controlled growth of GaSe on 2D graphene has potential to fabricate multifunctional integrated devices. However, the direct growth of GaSe on patterned graphene has rarely been reported. [17] Position-controlled growth of GaSe on a prepatterned large-area graphene substrate can be advantageous for fabricating large-scale GaSe-based detector array and other integrated devices.This report demonstrates the growth and fabrication of GaSe photodetector array on prepatterned graphene. The GaSe was grown on top of graphene using a molecular beam epitaxy (MBE) technique. Physical properties of the grown GaSe layer were investigated using X-ray diffraction (XRD), absorption, and Raman spectroscopies. GaSe-based photodetector diodes were fabricated and studied under the exposure of lights of different wavelengths and incident powers. Furthermore, 16 × 16 detectors of 40 × 40 um 2 were also fabricated and examined to demonstrate the feasibility of addressable photodetector array and mapping capability.

Growth Mode Transition in Two-Dimensional GaSe on Three-Dimensional GaN/Sapphire Platform: Implication for Self-Powered Photodetection

“…Post-transition metal chalcogenides, including the two-dimensional gallium monochalcogenide (2D-GMC) family, have been becoming a rising star in the field of condensed matter physics and offering opportunities for engineering novel optoelectronic applications in recent years, thanks to possessing unique mechanical, electronic, and optical properties with the large optical window in 2D limit. In particular, noncentrosymmetric ε-phase gallium selenide (GaSe) that is commonly observed in various synthetic methods is one of the potential candidates for electronics, second-harmonic generation, especially for photoelectrochemical and photodetection applications with low dark current, relatively high photoresponsivity, and fast response time. − In addition, many researchers have demonstrated that leveraging hybrid dimensionality figure of merits, such as integration of 2D-layered materials with 3D substrates/templates via heteroepitaxy, could be a crucial benefit to enhance the performance of 2D-based optoelectronic devices. In fact, that allows for improving optical absorption efficiency, forming type-II band alignment mixed-dimensional heterostructures, and reducing unintentional contamination during chemical/mechanical exfoliation. ,− During the past decade, many efforts have been made to fabricate 2D/3D mixed-dimensional heterostructures by either chemical or physical deposition methods.…”

A Systematic Study of the Temperature Dependence of the Dielectric Function of GaSe Uniaxial Crystals from 27 to 300 K

“…Gallium selenide (GaSe) is a compound in the III-VI group that has gained considerable interest recently due to its exceptional properties and potential applications in various fields including photodetectors [1][2][3][4][5][6], water splitting [6][7][8], lasers [9][10][11][12], and nonlinear optics [13][14][15]. GaSe can crystallize in four different polytypes, namely β-, ε-, γ-, and δ-phase structures, which correspond to the space groups P6 3 /mmc (D 4 6h ), P6m2(D 1 3h ), R3m (C 5 3v ), and P6 3 mc (C 4 6v ), respectively.…”

High Performance Graphene–C60–Bismuth Telluride–C60–Graphene Nanometer Thin Film Phototransistor with Adjustable Positive and Negative Responses

“…However, large‐scale array imaging is still a considerable challenge due to the engineering bottlenecks and theoretical limitations. [ 28 ] To name a few, clean transfer of 2D materials and uniform growth of QDs/nanowires are the primary technical bottlenecks to achieve a homogeneous preparation of the array unit. [ 29 ] Meanwhile, a high photoconductive gain is usually at the cost of sacrificing the response time due to the limitation of the defect state.…”