2D/3D Hybrid of MoS₂/GaN for a High-Performance Broadband Photodetector

Abstract

Narrow spectral sensitivity in materials is one of the crucial challenges to develop high-performance broadband photodetectors. Here, we design a heterostructure of two-dimensional molybdenum disulfide (MoS2) and epitaxial gallium nitride (GaN) films to create an enhanced spectral absorption profile. This combination utilizes complementary optical absorption of MoS2 (visible) and GaN (UV) driven by type II band alignment at their interface to showcase highly sensitive photodetectors spanning across the UV–NIR regime. Concurrently, the heterostructure exhibits significantly enhanced responsivity (order of 104 A/W) and external quantum efficiency that are 500% higher than the bare GaN photodetectors. Given the available scalable synthesis approaches that have now been designed by the research community for both constituent materials, the demonstration of this heterostructure as a broadband photodetector with high figures-of-merit opens opportunities in designing efficient optoelectronic junctions and imaging applications.

Large-Area Monolayer MoS2 Nanosheets on GaN Substrates for Light-Emitting Diodes and Valley-Spin Electronic Devices

“…where h is the Planck constant, c is the speed of light, R is the photoresponsibility as calculated based on eq 4, e is the charge of the electron, and λ is the wavelength of the illumination laser. 54 The EQE is calculated to be 6.6 × 10 5 % at the bias voltage of 3 V. A comparison of the performance parameters of the MoS 2 /GaN photodetector with previous reports is outlined in Table S1, 20,53−56 which means that the MoS 2 / GaN heterostructure shows potential application prospects in photodetectors.…”

“…However, the value of photoresponsivity is a little lower than the multilayer MoS 2 /GaN heterostructure due to the stronger absorption in multilayer MoS 2 samples. 20,54 We further analyze the external quantum efficiency (EQE) of the MoS 2 /GaN heterostructure-based photodetector, which refers to the photoconversion efficiency, and can be expressed by the following formula…”

“…Since the Fermi level of GaN is at a lower energy level than that of MoS 2 , the built-in electric field is directed from MoS 2 to GaN. The band alignment under bias voltage was illustrated based on the KPFM analysis, as shown in Figure c. ,, When a positive voltage is applied to GaN with respect to MoS 2 , the built-in potential will be offset, leading to a decrease in the effective barrier and more electrons can transport from MoS 2 to GaN, resulting in a high value of the current. Similarly, a low value of the current is observed owing to the reinforcing of the built-in potential when reverse-biased.…”

“…When the photogenerated holes are captured by the traps, hindering the recombination of excitons, then electrons are extracted from the source to maintain the charge neutrality of the channel, resulting in an ultrahigh photoresponsivity. However, the value of photoresponsivity is a little lower than the multilayer MoS 2 /GaN heterostructure due to the stronger absorption in multilayer MoS 2 samples. , We further analyze the external quantum efficiency (EQE) of the MoS 2 /GaN heterostructure-based photodetector, which refers to the photoconversion efficiency, and can be expressed by the following formula where h is the Planck constant, c is the speed of light, R is the photoresponsibility as calculated based on eq , e is the charge of the electron, and λ is the wavelength of the illumination laser . The EQE is calculated to be 6.6 × 10 5 % at the bias voltage of 3 V. A comparison of the performance parameters of the MoS 2 /GaN photodetector with previous reports is outlined in Table S1, ,− which means that the MoS 2 /GaN heterostructure shows potential application prospects in photodetectors.…”

van der Waals epitaxy of transition metal dichalcogenides via molecular beam epitaxy: looking back and moving forward

“…[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] Among these, a particular class of layered materials, i.e., transition metal dichalcogenides (TMDCs), has garnered significant interest, owing to their rich physics and fascinating potential applications. [35][36][37][38][39][40][41] TMDCs, just like graphene, can be scaled down to monolayers, although these TMDCs are three atoms thick instead of one. 42 TMDCs-based devices possess considerable charge carrier mobility and a semiconducting bandgap, making them suitable for switching applications, 25 and therefore, exhibit significant photoluminescence (PL) and intrinsic on-off current ratios as compared to graphene.…”