Theoretical Investigation of New Quantum-Cross-Structure Device as a Candidate beyond CMOS

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1067-B03-01

Theoretical Investigation of New Quantum-Cross-Structure Device as a Candidate beyond CMOS Kenji Kondo, Hideo Kaiju, and Akira Ishibashi Laboratory of Quantum Electronics, Research Institute for Electronic Science, Hokkaido University, Sapporo, 060-0812, Japan ABSTRACT We propose a new quantum cross structure (QCS) device as a candidate beyond CMOS. The QCS consists of two metal nano-ribbons having edge-to-edge configuration like crossed fins.The QCS has potential application in both switching devices and high-density memories by sandwiching a few molecules and atoms. The QCS can also have electrodes with different dimensional electron systems because we can change the widths, the lengths, and the heights of two metal nano-ribbons, respectively. Changing the dimensions of electron systems in both electrodes, we have calculated the current-voltage characteristics depending on the coupling constants between a molecule and the electrode. We find that the conductance peak is much sharper in case of weak coupling regardless of dimensions of electron systems in electrodes, compared to strong coupling case. We also find that the conductance peak of QCS having electrodes with two-dimensional electron systems (2DES) is much sharper than that of QCS having electrodes with three-dimensional electron systems (3DES) in case of strong coupling because of quantum size effect of 2DES. These results imply that the QCS with the very sharp conductance peak can serve as the devices to switch on and off by very small voltage change. INTRODUCTION Nowadays, many researchers have paid attention to post-silicon devices [1,2]. One of the several post-silicon devices is a cross-bar memory device based on molecular devices fabricated by nanoimprint lithography, which has achieved the production of 30-nm half-pitch patterning [3,4]. However, today’s production procedures such as nanoimprint lithography, and optical lithography, and electron-beam lithography, do not allow for the resolution to achieve sub-20-nm line-width structures. Recently, we have proposed a double nano-“baumkuchen” (DNB) structure, composed of two thin slices of alternating metal/insulator nano-“baumkuchen” as a lithography-free nanostructure fabrication technology [5,6], and a quantum cross structure device [7,8]. The schematic illustration of the fabrication procedure is shown in figure 1. First, the metal/insulator (organic film) spiral heterostructure is fabricated using a vacuum evaporator including a film-rolled-up system. Then, two thin slices of the metal/insulator nano-“baumkuchen” are cut out from the metal/insulator spiral heterostructure. Finally, the two thin slices are attached together face to face so that each stripe is crossing. The DNB has potential application in switching devices or high-density memories, the cross point of which can be scaled down to ultimate feature sizes of a few nanometers due to the film thickness determined by the metal-deposition rate, ranging from 0.01 nm/s to 1 nm/s. We call one element of the DNB structure a QCS de