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UBC Theses and Dissertations

Simulation and analysis of clocking and control for field-coupled quantum-dot nanostructures Chiu, Hsi Nien


Novel advancements in silicon dangling bond (SiDB) fabrication has led to logical circuitry at the atomic scale, with crucial building blocks including binary wires and logic gates experimentally demonstrated on the SiDB platform. However, complex SiDB circuitry will require clocking control for signal propagation and timing. This work proposes the use of control and clocking electrodes commonly presented in quantum-dot cellular automata (QCA) implementations for the SiDB platform and introduces PoisSolver, a simulation engine used to obtain clocking potentials in a SiDB system with complementary metal-oxide semiconductor (CMOS) metal layers. PoisSolver is built into the SiQAD computer aided design (CAD) tool, aiding circuit design by visualising electric potentials and providing potential solutions to other built-in SiQAD simulation engines. Utilising PoisSolver’s output and the electrode design in SiQAD, geometry agnostic methods are employed to estimate power characteristics for QCA’s columnar, wave, and USE clocking schemes. Parasitic power densities of these clocking schemes are estimated to be on the order of 10-100μW cm⁻² at 1GHz and 77K. The potentially low power dissipation of SiDBs is extremely attractive for low power applications. As a result, a novel CMOS-to-SiDB flash analog-to-digital converter (ADC) proof-of-concept is designed using PoisSolver and SiQAD as a case study. A 2-bit implementation of the flash ADC is estimated to perform on par with thermal-noise limited CMOS ADCs in the worst case, and approximately four orders of magnitude better in the best case, depending on the elasticity of SiDB relaxations.

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