Towards high-performance two-dimensional black phosphorus optoelectronic devices: the role of metal contacts

Abstract

The metal contacts on 2D black phosphorus field-effect transistor and photodetectors are studied. The metal work functions can significantly impact the Schottky barrier at the metal-semiconductor contact in black phosphorus devices. Higher metal work functions lead to larger output hole currents in p-type transistors, while ambipolar characteristics can be observed with lower work function metals. Photodetectors with record high photoresponsivity (223 mA/W) are demonstrated on black phosphorus through contact-engineering.

Generalized Scheme for High Performing Photodetectors with a p‐Type 2D Channel Layer and n‐Type Nanoparticles

“…The increasing rate (Δ I ph /Δ t ) of photocurrent is caused by the increase of carrier concentration and the existence of built‐in electric field related to the efficient charge transfer between BP and MoS 2 NPs. The responsivities, detectivities, and response times of the present MoS 2 NP–BP devices demonstrated obvious improvements over previous results for BP and BP junction photodevices . However, as the use of MoS 2 NPs as a light absorption layer in MIR range would be limited due to the large bandgap (>1.8 eV), the integration of BP with smaller bandgap semiconductor or metal NPs need to be further studied for performance improvements in MIR range compared to the reported BP photodetectors …”

“…The highest responsivities observed for this hybrid structure were 5000 A W −1 in the visible light range and 309 A W −1 in the near‐infrared range. These values are higher than those of reported BP and 2D BP–MoS 2 vertical photodiode photodetectors . These high values in MoS 2 NP–BP structure arise from the strong light absorption and p‐doping effect by charge transfer behavior.…”

“…Multilayer BP phototransistor/photodetectors operate over a broad wavelength range spanning from UV to mid‐infrared . However, their photoresponsivities are very low because of the weak light absorption and the lack of a built‐in electric field. With the aim of enhancing the performance of BP photodetector, we hybridized MoS 2 NPs with BP, shown in Figure a.…”

Selenium‐Doped Black Phosphorus for High‐Responsivity 2D Photodetectors

“…[ 31 ] As an anisotropic material, the transport property of BP is highly dependent on the crystal orientation, [ 47 ] the channel of the BP device in Figure 3 c,d is along zigzag direction, which is identifi ed by angle-resolved polarized Raman spectroscopy (ARPRS) ( Figure S7 in the Supporting Information). [ 48 ] As reported, [ 23,24,28,30,49 ] electron current of BP FETs is much lower than that of holes, which can be attributed to a large Schottky barrier height for electron injection. [ 23 ] Interestingly, the electron current of Sedoped BP FET levels up compared to that of the pristine one ( Figure S8, Supporting Information), indicating more electrons transporting between BP channel and metal electrodes with reduced Shottky barrier after Se dope.…”

Radiation effects on two-dimensional materials

“…Investigating the detection of visible and UV light by semiconducting 2DMs has led to a proliferation ofphotodetectors with responsivity spanning approximately 15 orders of magnitude (see Fig. 2a-d) across a wide variety of materials systems, including graphene [32][33][34][35][36][37][38] and reduced graphene oxide (rGO) [39,40]; black phosphorous [41][42][43][44]; III-VI layered compounds (GaX [45][46][47][48][49][50], InX [51][52][53][54], In 2 X 3 [55]); TMDs (MoS 2 [41,[56][57][58][59][60][61][62][63][64][65], ReS 2 [66] , WX 2 [64,[67][68][69][70]); and post-TMDs (SnS 2 [71][72][73]); Bi 2 Te 3 [74]. From this vast and everincreasing amount of data, there are several key points that emerge:…”