Skip to main content
eScholarship
Open Access Publications from the University of California

UC San Diego

UC San Diego Electronic Theses and Dissertations bannerUC San Diego

Atomic and electronic structures of oxides on III-V semiconductors :

Abstract

The surface reconstructions of decapped InAs(001) and In₀.₅₃Ga₀.₄₇As(001) have been studied using scanning tunneling microscopy (STM). Quantitative comparison of the In₀.₅₃Ga₀.₄₇As(001)-(4x2) and InAs(001)-(4x2) show the reconstructions are almost identical, but In₀.₅₃Ga₀.₄₇As(001)-(4x2) has at least a 4x higher surface defect density even on the best samples. For both In₀.₅₃Ga₀.₄₇As(001)-(4x2) and InAs(001)-(4x2), density functional theory (DFT) simulations at elevated temperature are consistent with the experimentally observed 300 K structure being a thermal superposition of three structures. The passivation of InAs(001) and InGaAs(001) surface using three different oxides (SiO, Ga₂O and In₂O) was studied using STM, STS, and DFT modeling of bonding and electronic structures. SiO molecules have higher self-binding energy so that they bond themselves and form nanoclusters on InAs(001)-(4x2) surface. Conversely, both Ga₂O and In₂O molecules bond to the As atoms at the edge of the rows. However, Ga2O molecules also bond to preexisting Ga₂O oxide on the surface. At full coverage with post-deposition annealing, SiO oxide remains as nanoclusters, Ga₂O oxide forms disordered structures with the large flat terraces on the surface, while In₂O oxide bonds with the trough In atoms to form new O-In bonding sites and forms ordered structures running in the [110] direction on In₀.₅₃Ga₀.₄₇As(001)-(4x2). STS results show that Ga₂O oxide does not passivate the interface nor unpin the In₀.₅₃Ga₀.₄₇As(001)-(4x2) surface consistent with its inability to form monolayer ordered islands on the surface; conversely, In₀.₅₃Ga₀.₄₇As(001)-(4x2) has an ordered monolayer coverage and is unpinned

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View