Abstract:Today, silicon is the most used material in photovoltaics, with the maximum conversion efficiency getting very close to the Shockley-Queisser limit for single-junction devices. Integrating silicon with higher band-gap ternary III-V absorbers is the path to increase the conversion efficiency. Here, we report on the first monolithic integration of Ga InP vertical nanowires, and the associated p-n junctions, on silicon by the Au-free template-assisted selective epitaxy (TASE) method. We demonstrate that TASE allo… Show more
“…We believe that the composition variation can be correlated with the switching of doping precursors during MOCVD growth. This is consistent with previous work where similar effects were observed 29 , 30 . Fig.…”
Direct epitaxial growth of III-Vs on silicon for optical emitters and detectors is an elusive goal. Nanowires enable the local integration of high-quality III-V material, but advanced devices are hampered by their high-aspect ratio vertical geometry. Here, we demonstrate the in-plane monolithic integration of an InGaAs nanostructure p-i-n photodetector on Si. Using free space coupling, photodetectors demonstrate a spectral response from 1200-1700 nm. The 60 nm thin devices, with footprints as low as ~0.06 μm2, provide an ultra-low capacitance which is key for high-speed operation. We demonstrate high-speed optical data reception with a nanostructure photodetector at 32 Gb s−1, enabled by a 3 dB bandwidth exceeding ~25 GHz. When operated as light emitting diode, the p-i-n devices emit around 1600 nm, paving the way for future fully integrated optical links.
“…We believe that the composition variation can be correlated with the switching of doping precursors during MOCVD growth. This is consistent with previous work where similar effects were observed 29 , 30 . Fig.…”
Direct epitaxial growth of III-Vs on silicon for optical emitters and detectors is an elusive goal. Nanowires enable the local integration of high-quality III-V material, but advanced devices are hampered by their high-aspect ratio vertical geometry. Here, we demonstrate the in-plane monolithic integration of an InGaAs nanostructure p-i-n photodetector on Si. Using free space coupling, photodetectors demonstrate a spectral response from 1200-1700 nm. The 60 nm thin devices, with footprints as low as ~0.06 μm2, provide an ultra-low capacitance which is key for high-speed operation. We demonstrate high-speed optical data reception with a nanostructure photodetector at 32 Gb s−1, enabled by a 3 dB bandwidth exceeding ~25 GHz. When operated as light emitting diode, the p-i-n devices emit around 1600 nm, paving the way for future fully integrated optical links.
“…The diffusion length is around $50 nm for all the samples. Taking into account the excellent crystal quality reported by Bologna et al on similar nanoobjects, 15 it is likely that the diffusion length is dominated by surface recombination and is insensitive to the increase in the dopant concentration. On the other side, this result confirms the reproducibility of the reported estimation method.…”
Section: Gx Respectively [Red Dots Inmentioning
confidence: 99%
“…14 The use of TASE has been recently extended to the growth of ternary InGaP NWs and the effect of p-and n-dopants on the crystal structure, composition of the alloy, and optical properties has been investigated. 15 In the present work, we report the first investigation of the electrical properties at the nanoscale of these InGaP NWs by electron beam induced current microscopy (EBIC) and I(V) measurements performed on single nanostructures. Two different sets of samples were analyzed: the first contains homogeneously n-doped InGaP NWs to examine the n-doping using a heterojunction with the p-Si substrate, while the second consists of InGaP NWs containing a p-n homo-junction and aims to study the nanoscale charge collection properties of these structures.…”
We report the analysis of the electrical properties of In xÀ1 Ga x P nanowires (NWs) grown by template-assisted selective epitaxy. The individual NW properties are investigated by means of electron beam induced current microscopy (EBIC) and current-voltage curves acquired on single nano-objects. First, a set of samples containing n-doped InGaP NWs grown on a p-doped Si substrate are investigated. The electrical activity of the hetero-junction between the NWs and the substrate is demonstrated and the material parameters are analyzed, namely, the n-doping level is determined in relation to the dopant flow used during the growth. These results were used to design and elaborate InGaP NWs containing a p-n homo-junction. The electrical activity of the homo-junction is evidenced using EBIC mapping on single NWs, and material parameters (namely, the doping and the minority carrier diffusion lengths) for the p-and n-doped InGaP segments are estimated. Finally, the first proof of a photovoltaic effect from the NW homo-junctions is obtained by photocurrent measurements of a contacted NW array under white light irradiation.
“…Due to the complex growth kinetics, the composition of III-V alloy NWs can be influenced by doping incorporation 86,87 . This is an important issue since many applications require doped ternary alloy materials (a common example is the use of InGaN for LEDs and InGaP and AlGaAs for tandem solar cells).…”
Section: Figure 12 A)mentioning
confidence: 99%
“…In this scenario, the use of CL is fundamental for the design of nanowires containing electrical junctions. A representative example is given by the work of Bologna and coauthors 86 who optimized the growth of InGaP NWs via template-assisted selective epitaxy (TASE). While a homogeneous composition was achieved in undoped wires, CL maps revealed a strong compositional variation in NWs containing an axial p-n junction (Figure 14a and b).…”
Nowadays the realization of market-competitive devices based on nanomaterials is a major challenge. Optimization of the device performance requires deep understanding of the physical phenomena at the nanoscale. In this context, electron beambased techniques become indispensable. Several instruments have been developed in the past decades to provide versatile diagnostic solutions for improving materials, designs and device fabrication. These characterization techniques applied to nanostructured semiconductors can help filling the gap between material science and engineering by bringing in light important physical parameters.In this Chapter, the family of electron beam-based techniques is briefly introduced. First, the electron beam/matter interaction is described both in physical and operational terms. In particular, different phenomena occurring when a flux of electron collides with a semiconductor material are discussed. Then, two main electron beam scanning techniques are discussed in the following sections: electron beam induced current microscopy and cathodoluminescence. After a short description of the fundamentals, for each technique a bibliographic review is presented to illustrate its applications to analyses of semiconductor nanowires.
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