Photocurrent generation mechanism in biased graphene found to be PV or bolometric
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Nano Focus
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anoscale electromechanical (NEM) switches can be used as relays, transistors, logic devices, and sensors, and compared with conventional semiconductor switches offer reduced power consumption and improved ON/OFF ratios. NEM switches operate by controlling the contact between terminals, where a physical gap is typically overcome by applying large voltages (4–20 V) across the terminals. This prevents low-power applications and strong adhesion forces can occur that dominate over the restoring force. Overcoming these problems, a group of researchers at the Korea Advanced Institute of Science and Technology (KAIST) and the Korea National NanoFab Center (NNFC) recently fabricated NEM devices with ultrathin physical gaps by creating a curved or “pipe clip” suspended electrode structure. These operate below 1 V and exhibit negligible leakage current and on/ off ratios of 1 × 106. As described in a letter published online on November 25, 2012 in Nature Nanotechnology (DOI: 10.1038/ NNANO.2012.208), Jeong Oen Lee of KAIST and co-researchers used a high-density plasma (HDP) method to deposit a sacrificial SiO2 layer that was
Photocurrent generation mechanism in biased graphene found to be PV or bolometric
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raphene has interesting optoelectronic properties due to its zero bandgap, electron–hole symmetry, and high carrier mobility. For example, graphene can convert absorbed light into photocurrent. The origin of this photoresponse in graphene junctions has been attributed to either thermoelectric or photovoltaic (PV) effects. However, identifying which photocurrent mechanism is
Electric Field (MV/m)
“Pipe clip” interface structure for nanoelectromechanical switching device operates below 1 V
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0 Electric-field distribution of the traditional plane structure (upper) and the proposed pipe clip structure (lower) for a nanoscale electromechanical switching device. Reproduced with permission from Nature Nanotech. 8 (2013), DOI: 10.1038/nnano.2012.208; p. 36. © 2013 Macmillan Publishers Ltd.
sandwiched between tungsten//tungsten/ titanium electrodes. This resulted in an ultrathin gap of
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