Resistive CrOx Thin Film for Single-electron Devices

Nanoelectronic devices such as single-electron transistors (SETs) and quantum-dot cellular automata (QCA) are superior to conventional electronic devices by CMOS technology in many aspects. Implementation of SETs in logic circuits is believed to increase packing density and might decrease power dissipation, and quantum-dot cellular automata takes advantage of quantum effects for its operation and offers low power dissipation and high density. The purpose of this dissertation is to evaluate single-electron devices using resistive microstrips, and to investigate their applicability for QCA device fabrication. In this dissertation, we present our work on the fabrication and characterization of SETs with resistive microstrip barriers. Different fabrication technologies, pattern designs, and materials were used in the fabrication of SETs with CrOx microstrips to investigate the electron transport mechanism of CrOx resistors and origin of the Coulomb blockade oscillations in the devices. Hypotheses of the junction formation are given as the explanation for the experimental results. Based on our experimental results, we conclude that resistive microstrip itself can not provide sufficient barriers to observe Coulomb blockade oscillations, and the formation of tunneling barriers capable of fulfilling the two requirements of Coulomb blockade remains crucial for the observation of Coulomb blockade phenomenon. To investigate the applicability of resistive microstrips to QCA devices, a QCA latch with CrOx microstrips was fabricated by two steps of e-beam lithography and shadow evaporation. The low temperature measurement showed that the CrOx microstrips can be used instead of multiple tunnel junctions (MTJ) in the clocked QCA devices, to suppress the cotunneling which severely impairs the ability of QCA cells to store information. By using CrOx microstrips instead of MTJs, the problem of junction random background charge compensation in extra dots of MTJs is eliminated and the design of QCA cells is greatly simplified.