Abstract:Formation of metal-semiconductor (M-S) contacts at sub-20 nanometer range is a key requirement for down-scaling of semiconductor devices. However, electrical measurements of M-S contacts at this scale have exhibited dramatic change in the current-voltage (I-V) characteristics compared to that of conventional (or planar) Schottky contacts. This change is actually attributed to the limited metal contact region where the transferred charge from the semiconductor into the metal is confined to a small surface area,… Show more
“…10 ). The enhanced current in the reverse bias regime is in agreement with the behavior of nanoscale Schottky junctions, which usually show smaller current under forward bias and inverse rectification under reverse bias 33 . Fig.…”
Section: Resultssupporting
confidence: 83%
“…Interestingly, in a nanoscale Schottky contact, the depletion width is reduced with decreasing the tip radius r . This effect leads to an increased tunneling probability at the interface in the reverse low-bias regime and the expectation of a higher current for smaller tip radius, which is in contrast with the observed higher absolute current in the case of Au-coated probes ( r < 35 nm radius of curvature), with respect to the PtIt-coated probes ( r < 25 nm radius of curvature) 33 . However, the tip radius of the curvature does not describe the actual probe/sample contact area during measurement.…”
The performance of energy materials hinges on the presence of structural defects and heterogeneity over different length scales. Here we map the correlation between morphological and functional heterogeneity in bismuth vanadate, a promising metal oxide photoanode for photoelectrochemical water splitting, by photoconductive atomic force microscopy. We demonstrate that contrast in mapping electrical conductance depends on charge transport limitations, and on the contact at the sample/probe interface. Using temperature and illumination intensity-dependent current–voltage spectroscopy, we find that the transport mechanism in bismuth vanadate can be attributed to space charge-limited current in the presence of trap states. We observe no additional recombination sites at grain boundaries, which indicates high defect tolerance in bismuth vanadate. These findings support the fabrication of highly efficient bismuth vanadate nanostructures and provide insights into how local functionality affects the macroscopic performance.
“…10 ). The enhanced current in the reverse bias regime is in agreement with the behavior of nanoscale Schottky junctions, which usually show smaller current under forward bias and inverse rectification under reverse bias 33 . Fig.…”
Section: Resultssupporting
confidence: 83%
“…Interestingly, in a nanoscale Schottky contact, the depletion width is reduced with decreasing the tip radius r . This effect leads to an increased tunneling probability at the interface in the reverse low-bias regime and the expectation of a higher current for smaller tip radius, which is in contrast with the observed higher absolute current in the case of Au-coated probes ( r < 35 nm radius of curvature), with respect to the PtIt-coated probes ( r < 25 nm radius of curvature) 33 . However, the tip radius of the curvature does not describe the actual probe/sample contact area during measurement.…”
The performance of energy materials hinges on the presence of structural defects and heterogeneity over different length scales. Here we map the correlation between morphological and functional heterogeneity in bismuth vanadate, a promising metal oxide photoanode for photoelectrochemical water splitting, by photoconductive atomic force microscopy. We demonstrate that contrast in mapping electrical conductance depends on charge transport limitations, and on the contact at the sample/probe interface. Using temperature and illumination intensity-dependent current–voltage spectroscopy, we find that the transport mechanism in bismuth vanadate can be attributed to space charge-limited current in the presence of trap states. We observe no additional recombination sites at grain boundaries, which indicates high defect tolerance in bismuth vanadate. These findings support the fabrication of highly efficient bismuth vanadate nanostructures and provide insights into how local functionality affects the macroscopic performance.
“…Thus, the smaller energy band width facilitates higher tunneling probability for electrons from the tip into n-Si substrate, leading to higher magnitude of the reverse tunneling current, for the positive sweep voltage at the substrate. This basic nano-Schottky model is detailed elsewhere 28,34 . For further understanding of the electric field enhancement at the nano-tip/Semiconductor interface, models for two probes with 15 nm and 5 µm radii are constructed using physics-based TCAD simulation to map the interface electric field.…”
Section: Resultsmentioning
confidence: 99%
“…The conductive-probe atomic force microscopy (C-AFM) has been used as a powerful tool to investigate the photodetection at the nano-scale MS junctions 28–30 . The main advantage of C-AFM electrical measurement is its ability to gather local conductivity information 31–33 .…”
Silicon (Si)-based photodetectors are appealing candidates due to their low cost and compatibility with the complementary metal oxide semiconductor (CMOS) technology. The nanoscale devices based on Si can contribute efficiently in the field of photodetectors. In this report, we investigate the photodetection capability of nano-Schottky junctions using gold (Au) coated conductive atomic force microscope (C-AFM) tips, and highly cleaned n-Si substrate interface. The Au nanotip/n-Si interface forms the proposed structure of a nano Schottky diode based photodetector. The electrical characteristics measured at the nanoscale junction with different Au nanotip radii show that the tunneling current increases with decreasing the tip radius. Moreover, the tunneling process and photodetection effects are discussed in terms of barrier width/height decrease at the tip-semiconductor interface due to the applied electric field as well as the generation of plasmon-induced hot-electron at the nanoparticle (i.e. C-AFM tip)/n-Si interface. Furthermore, the photodetection sensitivity is investigated and it is found to be higher for C-AFM tips with smaller radii. Moreover, this research will open a new path for the miniaturization of photodetectors with high sensitivity based on nano-Schottky interfaces.
“…It has been demonstrated that the tunneling current is a direct function of the electric eld at the nano metal/Si junction, and the I-V behavior is reproducible when using the same Au AFM probe on a clean n-Si surface. 12,33 Therefore, the drop in the tunneling current at the Au NP/n-Si interface at subsequent voltage sweeps, as shown Fig. 3, is a result of the reduction of the interface electric eld due to the charge screening effect from the Au-NP.…”
In this work, we investigate the time dependence of trapped charge in isolated gold nanoparticles (Au-NPS) dispersed on n-Si substrates, based on the electrical characteristics of nano metal–semiconductor junctions.
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