Scanning tunneling microscopy of point defects and interfaces in compound semiconductors

1995 ◽  
Author(s):  
J. F. Zheng ◽  
M. Salmeron ◽  
E. R. Weber
2020 ◽  
Vol 10 (1) ◽  
Author(s):  
N. V. Andreeva ◽  
A. Petraru ◽  
O. Yu. Vilkov ◽  
A. E. Petukhov

Abstract A combined study of local structural, electric and ferroelectric properties of SrTiO$$_{3}$$ 3 /La$$_{0.7}$$ 0.7 Sr$$_{0.3}$$ 0.3 MnO$$_{3}$$ 3 /BaTiO$$_{3}$$ 3 heterostructures was performed by Piezoresponse Force Microscopy, tunneling Atomic Force Microscopy and Scanning Tunneling Microscopy in the temperature range 30–295 K. The direct correlation of film structure (epitaxial, nanocrystalline or polycrystalline) with local electric and ferroelectric properties was observed. For polycrystalline ferroelectric films the predominant polarization state is defined by the peculiarity of screening the built-in field by positively charged point defects. Based on Scanning Tunneling Spectroscopy results, it was found that a sequent voltage application provokes the modification of local resistive properties related to the redistribution of point defects in thin ferroelectric films. A qualitative analysis of acquired Piezoresponse Force Microscopy, tunneling Atomic Force Microscopy and Scanning Tunneling Microscopy images together with Scanning Tunneling Spectroscopy measurements enabled us to conclude that in the presence of structural defects the competing processes of electron injection, trap filling and the drift of positively charged point defects drives the change of resistive properties of thin films under applied electric field. In this paper, we propose a new approach based on Scanning Tunneling Microscopy/Spectroscopy under ultrahigh vacuum conditions to clarify the influence of point defects on local resistive properties of nanometer-thick ferroelectric films.


1997 ◽  
Vol 474 ◽  
Author(s):  
Markus Kuhn ◽  
J. F. Anderson ◽  
Jeremy Lehman ◽  
Talib Mahmoud ◽  
Ulrike Diebold

ABSTRACTThe interaction of molecular oxygen, at room temperature, with a reduced TiO2(110) surface has been studied in situ by scanning tunneling microscopy (STM). Oxygen vacancies (point defects) were created on a clean TiO2(110) surface by annealing in ultra-high vacuum and successfully imaged on the atomic scale. These point defect sites were stable under ultrahigh vacuum conditions. During exposure to molecular oxygen, new point defects appear at different locations on the surface although their overall number is reduced. A mechanism for this dynamic healing process is proposed.


1990 ◽  
Vol 183 ◽  
Author(s):  
R. Wiesendanger ◽  
G. Tarrach ◽  
D. Buergler ◽  
L. Scandella ◽  
H.-J. Guentherodt

AbstractWe have studied point defects, linear defects as well as spatial transitions between ordered and disordered structures on silicon surfaces with atomic resolution by using scanning tunneling microscopy (STM). Point defects in the vicinity of multiple step edges as well as surface reconstructions at multiple step edges as high as 3 nm have been characterized by STM. STM images of partially disordered silicon surfaces prepared by laser and thermal annealing demonstrate the potential of STM for characterizing non-periodic surfaces on the atomic scale.


2010 ◽  
Vol 25 (3) ◽  
pp. 444-457 ◽  
Author(s):  
Sanju Gupta ◽  
John Farmer ◽  
Dario Daghero ◽  
Renato Gonnelli

We report temperature-dependent electrical resistivity (or dc conductivity, σdc) down to 4 K for pristine and gamma-irradiated microwave plasma-assisted chemical vapor-deposited boron-doped diamond films with [B]/[C]gas = 4000 ppm to gain insights into the nature of conduction mechanism, distribution, and kinetics of point defects generated due to gamma irradiation prompted by the article [Gupta et al., J. Mater. Res.24, 1498 (2009)]. The pristine samples exhibit typical metallic conduction up to 50 K and with reduction in temperature to 25 K, the σdc decreases monotonically followed by saturation at 4 K, suggesting “disordered” metal or “localized” behavior. For irradiated films, continuous increasing resistivity with decreasing temperature demonstrates semiconducting behavior with thermal activation/hopping conduction phenomena. It is intriguing to propose that irradiation leads to substantial hydrogen redistribution leading to unexpected low-temperature resistivity behavior. Scanning tunneling microscopy/spectroscopy helped to illustrate local grain and grain boundary effects.


Vacuum ◽  
1990 ◽  
Vol 41 (1-3) ◽  
pp. 591-595 ◽  
Author(s):  
G Cox ◽  
K.H. Graf ◽  
D Szynka ◽  
U Poppe ◽  
K Urban

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