Electron Spin Relaxation of Donors in Silicon Nanoelectronic Devices
Abstract
The environment interacts with the electron and leads to electron relaxation pro cesses. To measure the relaxation rate the system is disturbed from equilibrium. T1 time characterizes the time for the system to restore equilibrium. Understanding and controlling the spin-relaxation mechanism is crucial for real izing a spin-qubit based quantum computer. The spin-lattice relaxation time (T1) is one of the two important timescales of a qubit, and in addition, it can provide valu able information about the qubit and its interaction with the device environment. Here, we investigate the T1 time of electronic spins bound to donors in silicon in a scanning tunneling microscopy (STM) fabricated device. A tight-binding treatment of the electron-phonon problem is being developed. Together with Fermi’s Golden rule the T1 time of the system can be obtained with atomic level details. This method is extended to treat the multi-electron system, where the electron-electron interaction is captured by atomistic con?guration interaction method. We also show that under applied gate bias, an unconventional spin-orbit coupling the external electric ?eld and magnetic ?eld dominates over Rashba spin-orbit for donors in Si. Various spin relaxation mechanisms are investigated, considering both the valley repopulation and single valley e?ects. We ?nd that T1 is strongly dependent on the directions of the external magnetic and electric ?elds relative to the crystalline directions. We show good agreements between this theory and recent experimental measurements.
Degree
Ph.D.
Advisors
Rahman, Purdue University.
Subject Area
Engineering|Electrical engineering
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