UC Berkeley

Information, be it classical or quantum mechanical, requires representation in physical reality for processing and storage. Conventional classical computation utilizes the charge degree of freedom of carriers in semiconductors for encoding information; however, fundamental physical limitations will be reached within the next two decades preventing further improvements in computational capacity with charged-based devices. In recent years, the utilization of the spin states of charged carriers has shown remarkable promise for both enhancing the functionalities of classical computation devices and achieving quantum information processing. In this work, I explore this spin degree of freedom in donor-doped silicon metal-oxide-semiconductor (MOS) devices, which are promising architectures for the implementation of spin-based qubits in silicon for quantum information processing. The spin-dependent transport phenomena in such systems are studied systemically by electrically detected magnetic resonance (EDMR) techniques at X-band ($\approx9.5\:$GHz) and W-band ($\approx95\:$GHz), with corresponding Zeeman fields of $0.35\:$T and $3.5\:$T, respectively. It is found that direct spin-dependent scattering amongst conduction electrons and neutral donors gives rise to a much weaker contribution to spin-dependent transport than previously reported. Instead, the dominant spin-dependent processes in these systems are due to the polarization-dependent conduction electron mobility and subsequent polarization transfer from donor electrons. The technique of EDMR also allows us to perform {\it in situ} electron polarization detection, which is used to demonstrate spin drift and spin diffusion effects in silicon MOSFET devices. Towards the realization of donor spin-state readout, few-donor doped finFETs are also developed and the transport spectroscopy of such devices explored. These measurements provide invaluable insight into these interesting quantum devices and pave the way for the realization of spin-based computation.