eprintid: 1404597 rev_number: 38 eprint_status: archive userid: 608 dir: disk0/01/40/45/97 datestamp: 2013-09-11 20:54:16 lastmod: 2021-09-19 23:20:37 status_changed: 2013-09-11 20:54:16 type: article metadata_visibility: show item_issues_count: 0 creators_name: Sinthiptharakoon, K creators_name: Schofield, SR creators_name: Studer, P creators_name: Brazdova, V creators_name: Hirjibehedin, CF creators_name: Bowler, DR creators_name: Curson, NJ title: Investigating individual arsenic dopant atoms in silicon using low-temperature scanning tunnelling microscopy ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F60 divisions: F64 note: © 2014 IOP Publishing Ltd.Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. abstract: We study subsurface arsenic dopants in a hydrogen-terminated Si(001) sample at 77 K, using scanning tunnelling microscopy and spectroscopy. We observe a number of different dopant-related features that fall into two classes, which we call As1 and As2. When imaged in occupied states, the As1 features appear as anisotropic protrusions superimposed on the silicon surface topography and have maximum intensities lying along particular crystallographic orientations. In empty-state images the features all exhibit long-range circular protrusions. The images are consistent with buried dopants that are in the electrically neutral (D0) charge state when imaged in filled states, but become positively charged (D+) through electrostatic ionization when imaged under empty-state conditions, similar to previous observations of acceptors in GaAs. Density functional theory calculations predict that As dopants in the third layer of the sample induce two states lying just below the conduction-band edge, which hybridize with the surface structure creating features with the surface symmetry consistent with our STM images. The As2 features have the surprising characteristic of appearing as a protrusion in filled-state images and an isotropic depression in empty-state images, suggesting they are negatively charged at all biases. We discuss the possible origins of this feature. date: 2014-01-08 official_url: http://dx.doi.org/10.1088/0953-8984/26/1/012001 vfaculties: VMPS vfaculties: VMPS oa_status: green full_text_type: pub primo: open primo_central: open_green verified: verified_manual elements_source: WoS-Lite elements_id: 892407 doi: 10.1088/0953-8984/26/1/012001 lyricists_name: Bowler, David lyricists_name: Brazdova, Veronika lyricists_name: Curson, Neil lyricists_name: Hirjibehedin, Cyrus lyricists_name: Schofield, Steven lyricists_id: DBOWL76 lyricists_id: VBRAZ31 lyricists_id: NCURS27 lyricists_id: CHIRJ93 lyricists_id: SSCHO23 full_text_status: public publication: JOURNAL OF PHYSICS-CONDENSED MATTER volume: 26 number: 1 article_number: ARTN 012001 issn: 0953-8984 citation: Sinthiptharakoon, K; Schofield, SR; Studer, P; Brazdova, V; Hirjibehedin, CF; Bowler, DR; Curson, NJ; (2014) Investigating individual arsenic dopant atoms in silicon using low-temperature scanning tunnelling microscopy. JOURNAL OF PHYSICS-CONDENSED MATTER , 26 (1) , Article ARTN 012001. 10.1088/0953-8984/26/1/012001 <https://doi.org/10.1088/0953-8984%2F26%2F1%2F012001>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/1404597/1/0953-8984_26_1_012001.pdf