Broadband, Polarization-Sensitive Photodetector Based on Optically-Thick Films of Macroscopically Long, Dense and Aligned Carbon Nanotubes

Abstract

Increasing performance demands on photodetectors and solar cells require the development of entirely new materials and technological approaches. We report on the fabrication and optoelectronic characterization of a photodetector based on optically-thick films of dense, aligned, and macroscopically long single-wall carbon nanotubes. The photodetector exhibits broadband response from the visible to the mid-infrared under global illumination, with a response time less than 32 μs. Scanning photocurrent microscopy indicates that the signal originates at the contact edges, with an amplitude and width that can be tailored by choosing different contact metals. A theoretical model demonstrates the photothermoelectric origin of the photoresponse due to gradients in the nanotube Seebeck coefficient near the contacts. The experimental and theoretical results open a new path for the realization of optoelectronic devices based on three-dimensionally organized nanotubes.

Electronics and optoelectronics of quasi-1D layered transition metal trichalcogenides

“…While time resolved measurements have been performed on bulk-like nanoribbons (3 μm thick) 173 , atomically thin crystals have yet to be investigated and it remains to be seen whether the TMTCs present similar many body interactions (exciton-exciton annihilation) as the TMDCs in atomically thin samples [201][202][203][204][205] . Perhaps the most intriguing direction though is the application of MX3s in creating on-chip polarizers [36][37][38][39] , polarization sensitive photodetectors [40][41][42] , and devices with polarized light emission 28, 43,44 . Finally, the TMTCs must be contrasted with the recently (re)discovered anisotropic 2D materials black phosphorus and rhenium disulphide (ReS2).…”

“…[25][26][27][28][29][30][31] This anisotropy lends an additional degree of freedom in the fabrication of next generation electronics such as high mobility transistors benefiting from reduced backscattering from hot electrons [32][33][34] and novel integrated digital inverters 35 . More than this, these materials have great potential in electronics that rely on the generation and detection of polarized light, i.e, on-chip polarizers [36][37][38][39] , polarization sensitive photodetectors [40][41][42] , and polarized light emission 28,43,44 . Titanium trisulfide (TiS3), in particular, has gained recent attention as it presents a robust direct band gap of ~1 eV 45,46,47 which varies little with layer thickness or stacking order.…”

NanoJapan: international research experience for undergraduates program: fostering U.S.-Japan research collaborations in terahertz science and technology of nanostructures

“…Some of the ongoing research projects include active and/or plasmonic THz sources and detectors based on graphene, [8][9][10] development of THz polarizers 11,12 and detectors [13][14][15] based on aligned single-wall carbon nanotubes, ultrafast optical spectroscopy of coherent THz phonons in carbon nanomaterials, [16][17][18] and 3D micro-fabrication of single-wall carbon nanotube/polymer composites by two-photon polymerization lithography. 19 The electromagnetic spectrum from 0.1 to 10 THz offers many opportunities to study physical phenomena, with potential payoff in numerous technologies.…”

Identifying signatures of photothermal current in a double-gated semiconducting nanotube

“…The importance of photothermal effects has been suggested in the context of measurements of bulk SWNT films [12,13,14] and very recently, SPCM work on graphene and individual metallic SWNTs has emphasized the importance of photothermal mechanisms in materials with no or small bandgaps [22,26].…”

“…These properties make SWNTs an ideal platform for exploring photocurrent generation with SPCM. In early single-walled nanotubes SPCM work the interpretation of photocurrent was mostly based on photovoltaic mechanisms [6,7,8,9,11].The importance of photothermal effects has been suggested in the context of measurements of bulk SWNT films [12,13,14] and very recently, SPCM work on graphene and individual metallic SWNTs has emphasized the importance of photothermal mechanisms in materials with no or small bandgaps [22,26].The question of the role of photothermal mechanisms in larger bandgap semiconducting nanotubes has been studied very recently in double-gated [26] and single-gated [27] suspended carbon nanotube devices.These two studies report contradictory results, leaving the understanding of fundamental mechanisms underlying photocurrent generation in semiconducting nanotubes unclear.Here we report on the study of a suspended semiconducting nanotube device where we show that both photovoltaic and photothermal mechanisms compete in the generation of photocurrent. In particular, we find that the dominant or non-dominant character of one or the other processes is a function of the doping profile and that the magnitude of each contribution is strongly influenced by the band alignment with the metal contacts through the resulting contact resistance.…”