Surface plasmon enhanced infrared photodetection

Infrared photodetectors have been used extensively in biomedicine, surveillance, communication and astronomy. However, state of the art technology based on III-V and II-VI compounds still lacks excellent performance for high-temperature operation. Surface plasmon polaritons (SPPs) have demonstrated their capability in improving the light detection from visible to infrared wave range due to their light confinement in subwavelength scale. Advanced fabrication techniques such as electron-beam lithography (EBL) and focused ion-beam (FIB), and commercially available numerical design tool like Finite-Difference Time-Domain (FDTD) have enabled rapid development of surface plasmon (SP) enhanced photodetectors. In this review article, the basic mechanisms behind the SP-enhanced photodetection, the different type of plasmonic nanostructures utilized for enhancement, and the reported SP-enhanced infrared photodetectors will be discussed.

Plasmonic semiconductor nanogroove array enhanced broad spectral band millimetre and terahertz wave detection

High-performance uncooled millimnetre and terahertz wave detectors are required as a building block for a wide range of applications.The state-of-the art technologies,however,are plagued by low sensitivity,narrow spectral bandwidth,and complicated architecture.Here,we report semiconductor surface plasmon enhanced high-performance broadband millimetre and terahertz wave detectors which are based on nanogroove InSb array epitaxially grown on GaAs substrate for room temperature operation.By making a nanogroove array in the grown InSb layer,strong millimetre and terahertz wave surface plasmon polaritons can be generated at the InSb-air interfaces,which results in significant improvement in detecting performance.A noise equivalent power(NEP)of 2.2× 10^(-14)WHz^(-1/2) or a detectivity(D)of 2.7× 10^(12)cmHz^(1/2) W^(-1) at 1.75 mm(0.171 THz)is achieved at room temperature.By lowering the temperature to the thermoelectric cooling available 200 K,the corresponding NEP and D'of the nanogroove device can be improved to 3.8× 10^(-15)WHz^(-1/2) and 1.6× 10^(13) cm Hz^(-1/2) w^(-1),respectively.In addition,such a single device can perform broad spectral band detection from 0.9 mm(0.330 THz)to 9.4 mm(0.032 THz).Fast responses of 3.5μs and 780 ns are achieved at room temperature and 200 K,respectively.Such high-performance millimnetre and terahertz wave photodetectors are useful for wide applications such as high capacity communications,walk-through security,biological diagnosis,spectroscopy,and remote sensing.In addition,the integration of plasmonic semiconductor nanostructures paves a way for realizing high performance and multifunctional long-wavelength optoelectrical devices.

Antenna-assisted subwavelength metal–InGaAs–metal structure for sensitive and direct photodetection of millimeter and terahertz waves

Millimeter and terahertz wave photodetectors have a wide range of applications. However, the state-of-the-art techniques lag far behind the urgent demand due to the structure and performance limitations. Here, we report sensitive and direct millimeter and terahertz wave photodetection in compact InGaAs-based subwavelength ohmic metal–semiconductor–metal structures. The photoresponse originates from unidirectional transportation of nonequilibrium electrons induced by surface plasmon polaritons under irradiation. The detected quantum energies of electromagnetic waves are far below the bandgap of InGaAs, offering, to the best of our knowledge, a novel direct photoelectric conversion pathway for InGaAs beyond its bandgap limit. The achieved room temperature rise time and noise equivalent power of the detector are 45 μs and 20 pW · Hz^(-1∕2), respectively,at the 0.0375 THz(8 mm) wave. The detected wavelength is tunable by mounting different coupling antennas.Room temperature terahertz imaging of macroscopic samples at around 0.166 THz is also demonstrated. This work opens an avenue for sensitive and large-area uncooled millimeter and terahertz focal planar arrays.

Epitaxial indium antimonide for multiband photodetection from IR to millimeter/terahertz wave

Conventional photodetection converts light into electrical signals only in a single electromagnetic waveband.Multiband detection technology is highly desirable because it can handle multispectral information discrimination,identification,and processing.Current epitaxial solid-state multiband detection technologies are mainly within the IR wave range.Here,we report epitaxial indium antimonide on gallium arsenide for IR and millimeter/terahertz wave multiband photodetection.The photoresponse originates from interband transition in optoelectrical semiconductors for IR wave,and surface plasmon polaritons induced nonequilibrium electrons for a millimeter/terahertz wave.The detector shows a strong response for an IR wave with a cutoff wavelength of 6.85 μm and a blackbody detectivity of 1.8×10^(9) Jones at room temperature.For a millimeter/terahertz wave,the detector demonstrates broadband detection from 0.032 THz(9.4 mm)to 0.330 THz(0.9 mm);that is,from Ka to the W and G bands,with a noise equivalent power of 1.0×10^(-13) W Hz^(-1/2) at 0.270 THz(1.1 mm)at room temperature.The detection performance is an order of magnitude better while decreasing the temperature to 170 K,the thermoelectric cooling level.Such detectors,capable of large scale and low cost,are promising for advanced uncooled multiband detection and imaging systems.