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Ashwell G.J.,Lancaster University | Ashwell G.J.,Bangor University | Phillips L.J.,Bangor University | Robinson B.J.,Lancaster University | And 13 more authors.
ACS Nano

The highly doped electrodes of a vertical silicon nanogap device have been bridged by a 5.85 nm long molecular wire, which was synthesized in situ by grafting 4-ethynylbenzaldehyde via C-Si links to the top and bottom electrodes and thereafter by coupling an amino-terminated fluorene unit to the aldehyde groups of the activated electrode surfaces. The number of bridging molecules is constrained by relying on surface roughness to match the 5.85 nm length with an electrode gap that is nominally 1 nm wider and may be controlled by varying the reaction time: the device current increases from ≤1 pA at 1 V following the initial grafting step to 10-100 nA at 1 V when reacted for 5-15 min with the amino-terminated linker and 10 μA when reacted for 16-53 h. It is the first time that both ends of a molecular wire have been directly grafted to silicon electrodes, and these molecule-induced changes are reversible. The bridges detach when the device is rinsed with dilute acid solution, which breaks the imine links of the in situ formed wire and causes the current to revert to the subpicoampere leakage value of the 4-ethynylbenzaldehyde-grafted nanogap structure. © 2010 American Chemical Society. Source

Quaresma H.J.,University of Lisbon | Quaresma H.J.,Semefab Scotland Ltd. | Dos Santos P.M.,University of Lisbon | Serra A.C.,University of Lisbon
Electronics Letters

The effect of temperature on substrate coupling is reported for the first time. Modelling and experimental results are presented, showing a significant linear dependence of the substrate resistance with temperature in the range between 257 and 418K. The observed decrease in substrate resistance at lower temperatures implies that the substrate noise coupling could be seriously underestimated if the temperature effect is not taken into account. These results reveal the importance of including the effects of temperature on the substrate resistance models for the correct modelling of the substrate noise coupling. © 2011 The Institution of Engineering and Technology. Source

Balachandran A.,University of Sheffield | Sweet M.,University of Sheffield | Ngwendson L.,University of Sheffield | Sankara Narayanan E.M.,University of Sheffield | And 3 more authors.
Proceedings of the International Symposium on Power Semiconductor Devices and ICs

In this paper, we report the experimental results of a 3.3kV rated CIGBT (Clustered Insulated Gate Bipolar Transistor) with planar gates in non-punch through technology (NPT) with RTA anode. Previously it was reported that for identical turn-off losses the on-state voltage of the 3.3kV NPT-CIGBT is less than 0.7V as compared to that of a commercially available FS-IGBT. Herein we show that due to the low saturation current density, the CIGBT has a rugged short circuit performance, as measured to be of more than 100μs at 25°C which is much higher than any MOS controlled bipolar device ever reported. Furthermore, results also show that the use of the RTA anode compared to the diffused anode helps in reducing the turn-off losses by about 50% without affecting the Vce(sat) of the device. © 2012 IEEE. Source

Balachandran A.,University of Sheffield | Sweet M.R.,University of Sheffield | Luther-King N.,University of Sheffield | Narayanan E.M.S.,University of Sheffield | And 3 more authors.
IEEE Transactions on Electron Devices

In this paper, we report the experimental results of a 3.3-kV-rated clustered insulated gate bipolar transistor (CIGBT) with planar gates in nonpunchthrough technology (NPT) and rapid thermal annealing (RTA) anode. Previously, it had been shown that, for identical turn-off losses, the on -state voltage of the 3.3-kV CIGBT is more than 0.7 V lower than that of an equivalent IGBT. Herein, we show that, due to the low saturation current density, the CIGBT has a rugged short-circuit performance of more than 10 $\mu\hbox{s even at 125$C. Furthermore, results also show that the use of the RTA anode, as compared with, the diffused anode helps in reducing the turn-off losses by about 50% without affecting the V \rm ce(sat) value of the device. © 2012 IEEE. Source

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