Doctor of Philosophy, The Ohio State University, 2018, Physics

This thesis addresses scanning tunneling microscopy (STM) studies of metal defects in GaAs(110). Single-atom defects are useful for their potential applications in developing nano-scale miniaturized or new types of optical, magnetic, and electronic devices, as well as expanding our understanding of atomic-scale interactions. STM is used to measure physical and electronic properties of surface and near-surface materials with atomic resolution, but affects the properties of defects being studied. Zn-doped GaAs(110) is one of the most popular commercially used semiconductor materials, and is well-understood on the macroscopic scale. By studying individual Zn defects at a wider range of doping levels than previously studied, we discovered three types of defect-based conductivity caused by dopant interactions that inform macroscopic doped semiconductor properties and atomic-scale defect properties. Additionally, we tuned these properties using electronic fields and doping level, laying the groundwork for Zn defects in solotronic or nanoscale devices. Additionally, erbium, an element with useful optical properties, has been studied on GaAs(110) for the first time, and been shown to have four types of interaction with the host surface. This improved our understanding of the significance of the interaction strength of atoms with host materials on defect charge state and electronic properties. The techniques developed in studying Zn and Er atoms have yielded preliminary results for new properties of Mn and Co atoms and the first studies of V atoms on GaAs(110).

Committee: Jay Gupta (Advisor); Amy Connolly (Committee Member); Roland Kawakami (Committee Member); Mohit Randeria (Committee Member) Subjects: Condensed Matter Physics; Physics