High and Fast Response of a Graphene–Silicon Photodetector Coupled with 2D Fractal Platinum Nanoparticles

Abstract

However, the main drawback of chemical doping methods is the instability of molecular dopants, which would weaken the enhancement during storage. [5] Besides, chemical doping may even damage Gr. [6] Thereby, chemical doping methods are not suitable for the practical application of GrSi PDs.Since intensive plasmons can be aroused inside transition metals, the utilization of clusters of transition metal for the enhancement of photovoltaic devices has already been reported. [7] Recently, charge transfer between Gr and metal nanoparticles (NPs) has also been demonstrated in Gr-based optoelectronic devices. [8] It is believed that the NPs of high work function metal can effectively dope Gr with nonequilibrium holes and tune the Fermi level of Gr. Previously, we demonstrated that coupling Gr with platinum (Pt) NPs can significantly improve absorption of Gr-Si solar cells. [9] However, metal NPs agglomerate easily due to their large surface area. When NPs form large clusters, they will block the incident light instead of enhancing the absorption. There are some reports which proposed polystyrene-sphere methods to fabricate NPs array, [8a,10] but the fabrication process limits the morphology of NPs. Therefore, modification of metal NPs is needed to maximize the absorption enhancement.Moreover, with metal nanostructure or even metal fractal metasurface, [11] absorption of Gr-Si detectors can be improved even more. However, building a fractal metasurface of noble metal often requires liftoff process, which is complex and expensive. Recently, Jung et al. proposed a scalable synthesis method of 2D fractal Pt NPs with oleic-acid-in-water emulsion. [12] It provides a convenient way to improve the performance of Gr-Si detectors. 2D fractal Pt NPs can offer plasmonic enhancement that is similar to a fractal metasurface. On the other hand, the extensive morphology of NPs is helpful in getting a uniform film instead of aggregation. [13] This ensures maximal plasmonic enhancement. We can even modify the synthesis method to change the morphology of NPs to meet different requirements on detectors. Therefore, it would be interesting to investigate the enhancement on Gr-Si detectors with fractal NPs.In this work, we report the fabrication and characterization of fractal Pt NPs coupled Gr-Si PDs. With modified emulsion method, we can massively synthesized 2D fractal Pt NPs. With

Progress of Graphene–Silicon Heterojunction Photovoltaic Devices

“…Decorating Gr with silver nanowire network or CNT network has been proved to effectively decrease the sheet resistance of Gr . If the nanowire network is replaced by the fractal nanoparticles as Huang et al demonstrated with Gr/Si photodetectors, decoration layer can tune the reflection and the conductivity of Gr/Si solar cells simultaneously. Because several certain optimizations, i.e., AR and doping, are necessary for producing highly efficient Gr/Si solar cells, the multifunctional techniques can simplify the fabrication process, which will be warmly welcomed by the industry.…”

Graphene-Based Semiconductor Heterostructures for Photodetectors

“…Recently, a variety of graphene/Si-based structures have been proposed to improve the device performance. A new approach of integrating graphene/Si PD with two-dimensional (2D) Pt nanoparticles (NPs) has proven to enhance the R and response time of the PD at the same time, as shown in Figure 1 d [ 29 ]. Furthermore, the work function of graphene is increased by the physical doping with Pt NPs, thereby heightening the barrier of the Schottky junction, resulting in faster response and higher sensitivity, as shown in Figure 1 e,f.…”

“…The inset shows schematic diagram of a Si-graphene PD with fractal Pt NPs; ( e ) Ultraviolet photoelectron spectroscopy data of graphene-Si PDs with and without fractal Pt NPs, showing the effect of physical doping on the Fermi level; ( f ) Transient photovoltage characteristics of graphene-Si PDs with and without fractal Pt NPs under 532 nm pulse laser. Reproduced with permission for Figure 1 d–f from 2017 Advanced Optical Materials [ 29 ].…”

“…Chemical vapor deposition (CVD)-grown graphene was first employed in graphene/Si heterojunctions, resulting in 65% external quantum efficiency (EQE) [ 24 ], which served as the prototype for the subsequent intensive studies on the graphene TCEs-based various kinds of semiconductor hybrid heterojunctions for high-efficiency PDs [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ,…”

Camphor-Based CVD Bilayer Graphene/Si Heterostructures for Self-Powered and Broadband Photodetection

“…Thus, graphene is viewed as an ideal material to replace metal contacts and transparent conducting oxide (TCO) electrodes (e.g., indium tin oxide (ITO), indium zinc oxide (IZO), and fluorine-doped tin oxide (FTO)) in optoelectronic devices for forming ultra-shallow junctions with ultra-broadband optical absorption [ 18 , 19 , 20 ]. After the first graphene/Si Schottky PDs reported by M. Amirmazlaghani et al [ 21 ], the fast development of graphene/Si Schottky PDs is targeted specifically at the enhancement of the responsivity by employing Si nanostructures and chemical doping, as well as metal nanoparticles (such as Au and Pt) [ 22 , 23 , 24 , 25 ]. However, the complex, high-cost, and environmentally unfriendly processes of the above-mentioned methods have hindered the practical applications of graphene/Si PDs and integration with complementary metal–oxide–semiconductor (CMOS) processes.…”