Metal losses affect the performance of every plasmonic or metamaterial structure; dealing with them will determine the degree to which these structures will find practical applications. Loss happensThe last decade and a half has seen a steady rise of interest in plasmonics and metamaterials (P&M), a duo of closely related fields. The inspiration driving P&M research is the enticing prospect of concentrating and manipulating the electromagnetic field on the sub-wavelength scale to achieve unprecedented enhancement of linear and nonlinear optical processes, and develope nano-scale optical interconnects, optical cloaking, and super-resolution imaging [1][2][3]. Inspired by a few visionaries, P&M research has been enabled by the determined work of an army of engineers and scientists in microelectronics research who have been making steady advances in nanofabrication. However, when it comes to the materials used in P&M, their palette has remained sparse and unchanged, relying mostly on the metals used in reflection optics, predominantly silver and gold. The reason for the choice of these two noble metals is obviously the low rate of scattering of free electrons in them, which leads to high conductivity in the RF range and high reflectivity in the optical range. And yet, after decade-long effort, which did produce attention-grabbing results, the P&M community is beginning to face the unpleasant fact that, even in the noblest of metals, losses in the optical range (and here we include near-and mid-infrared regions) are still too high to make most, if not all, practical P&M devices. At this time, the one and only wide-spread practical application of plasmonics is surface enhanced Raman scattering (SERS) [4] which predates the term "plasmonics" itself, whereas the best results in nano-antennas and metamaterials have been attained in the microwave range, where these structures have been known, albeit under a different nom-de-guerre "artificial dielectrics" [5], since the early 1950s.If one is to summarize the current state of efforts to enhance performance of various optical devices using P&M, it can be done by noticing that while inefficient devices can indeed be improved, the performance of any relatively efficient device will only deteriorate, as loss in the metal will exceed whatever improvement the field concentration achieves. That is why for fluorescence sensors, where the absolute efficiency (light out vs. light in) is typically quite low, P&M does offer some promise. (Raman scattering can be thought of as fluorescence with efficiency approaching zerohence the aforementioned spectacular success of SERS!) But when it comes to the devices where the efficiency must be high such as light sources and detectors, solar cells, interconnects, switches

We experimentally demonstrate an on-chip nanoscale silicon surface-plasmon Schottky photodetector based on internal photoemission process and operating at telecom wavelengths. The device is fabricated using a self-aligned approach of local-oxidation of silicon (LOCOS) on silicon on insulator substrate, which provides compatibility with standard complementary metal-oxide semiconductor technology and enables the realization of the photodetector and low-loss bus photonic waveguide at the same fabrication step. Additionally, LOCOS technique allows avoiding lateral misalignment between the silicon surface and the metal layer to form a nanoscale Schottky contact. The fabricated devices showed enhanced detection capability for shorter wavelengths that is attributed to increased probability of the internal photoemission process. We found the responsivity of the nanodetector to be 0.25 and 13.3 mA/W for incident optical wavelengths of 1.55 and 1.31 μm, respectively. The presented device can be integrated with other nanophotonic and nanoplasmonic structures for the realization of monolithic opto-electronic circuitry on-chip.

We report an on-chip integrated metal graphene–silicon plasmonic Schottky photodetector with 85 mA/W responsivity at 1.55 μm and 7% internal quantum efficiency. This is one order of magnitude higher than metal–silicon Schottky photodetectors operated in the same conditions. At a reverse bias of 3 V, we achieve avalanche multiplication, with 0.37A/W responsivity and avalanche photogain ∼2. This paves the way to graphene integrated silicon photonics.

The best performing modern optoelectronic devices rely on single-crystalline thin-film (SC-TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low-cost solution-based methods, have achieved substantial success in various optoelectronic devices including solar cells, lasers, light-emitting diodes, and photodetectors. However, to date, the performance of these perovskite devices based on polycrystalline thin-film active layers lags behind the epitaxially grown semiconductor devices. Here, a photodetector based on SC-TF perovskite active layer is reported with a record performance of a 50 million gain, 70 GHz gain-bandwidth product, and a 100-photon level detection limit at 180 Hz modulation bandwidth, which as far as we know are the highest values among all the reported perovskite photodetectors. The superior performance of the device originates from replacing polycrystalline thin film by a thickness-optimized SC-TF with much higher mobility and longer recombination time. The results indicate that high-performance perovskite devices based on SC-TF may become competitive in modern optoelectronics.

Abstract