2026-09-19T23:15:06Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/78351 2023-07-11 col_2142_5131 col_2142_8888 com_2142_5130 com_2142_8887 com_2142_234

Lyding, Joseph W. Lyding, Joseph W. Bellon, Pascal Dallesasse, John M. Liu, Gang L. Olewicz, Tomasz 2015-07-22T22:16:29Z 2015-07-22T22:16:29Z 2015-05 2015-04-09 The thermally-activated coexistence of two diffusion mechanisms, adatom jump and exchange, is a phenomenon that has important potential application in fabrication of quantum dot based devices. If one can initiate the occurrence of a particular diffusion mechanism by changing the temperature, then it is possible to control the moment when an adatom is incorporated into the surface layer. The buried adatom could then serve as a nucleation center for growth of a nanostructure. This dissertation shows the first experimental evidence for the temperature-activated coexistence of two surface diffusion mechanisms, the adatom jump and adatom exchange, observed in a W on W(100) system. The adatom exchange was identified as the primary diffusion mechanism, and it is activated on a time scale of seconds at temperatures around 650 K. The occurrence of the secondary diffusion mechanism, adatom jump, was observed on a time scale of seconds at temperatures around 700 K. The experiments were conducted using a Field Ion Microscope (FIM) under Ultra-High Vacuum (UHV) conditions (~ 10-11 Torr). The activation energy for the exchange in a W on W(100) system was found to be 1.6 ± 0.24 eV. For the jump, the activation energy was estimated as ~2.1 eV. These values are in very good agreement with results from Density Functional Theory (DFT) calculations. Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2015-07-22 without embargo terms The student, Tomasz Olewicz, accepted the attached license on 2015-04-05 at 23:02. The student, Tomasz Olewicz, submitted this Dissertation for approval on 2015-04-05 at 23:56. This Dissertation was approved for publication on 2015-04-09 at 11:50. DSpace SAF Submission Ingestion Package generated from Vireo submission #7791 on 2015-07-22 at 10:31:26 Made available in DSpace on 2015-07-22T22:16:29Z (GMT). No. of bitstreams: 3 OLEWICZ-DISSERTATION-2015.pdf: 5627811 bytes, checksum: c7af6728817e92b30728584c2fa1bddf (MD5) Olewicz_Tomasz.docx: 14794852 bytes, checksum: f87b244e419d2098ec535fa81c4906b0 (MD5) LICENSE.txt: 4211 bytes, checksum: 27d924fe443966e18676b5046311aee1 (MD5) Previous issue date: 2015-04-09 application/pdf http://hdl.handle.net/2142/78351 en Copyright 2015 Tomasz Olewicz surface diffusion thungsten Coexistence of surface diffusion mechanisms: jump and exchange for W on W(100) text text 2015-5 Electrical & Computer Eng Electrical & Computer Engr University of Illinois at Urbana-Champaign Dissertation Ph.D.