Atomically precise signatures of native subsurface As monovacancy defect in GaAs studied by STM imaging and DFT calculations
- Type
- Article
- Citation
- SOLID STATE COMMUNICATIONS, v.405
- Issued Date
- 2025-11
- Abstract
- We conducted scanning tunneling microscopy (STM) measurements and density functional theory (DFT) calculations to investigate surface arsenic vacancies (V-As) and intrinsic subsurface V-As in GaAs(110), revealing distinct STM features and symmetries depending on their depth from the surface. A surface V-As appears as a symmetric dark contrast at the missing As site with estimated size of similar to 21.8 A(2). In contrast, a second-layer V-As exhibits an asymmetric two-lobe darker contrast, due to relaxation and charge accumulation in the underlying Ga atoms. A third-layer V-As, however, shows a symmetric "butterfly-like" dark contrast, caused by charge accumulation in the lower layers along with charge depletion around the central surface As atom. DFT calculations using the modified Becke-Johnson local density approximation (mbJ-LDA) reveal that V-As in bulk GaAs introduce slightly dispersed, partially-filled gap states near the conduction band, confirming previous theoretical predictions. The above findings show key features to distinguish surface and native subsurface V-As relative to their location from the surface via STM. Moreover, our findings reveal details into the structural, energetic, and electronic properties of V-As in bulk GaAs, which can provide valuable insights into the desired V-As-induced below-band gap excitation in GaAs for terahertz and optoelectronic device applications.
- Publisher
- PERGAMON-ELSEVIER SCIENCE LTD
- ISSN
- 0038-1098
- Appears in Collections:
- Department of Chemistry > 1. Journal Articles
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