Surface-defect formation on heavily doped InAs and GaAs layers studied by scanning tunneling microscopy

1996 ◽  
Vol 53 (8) ◽  
pp. 4565-4569 ◽  
Author(s):  
Hiroshi Yamaguchi ◽  
Yoshiji Horikoshi
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Surface Defect ◽  
Defect Formation ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Heavily Doped

Studies of Point Defect Formation and Self-Compensation in Indium Doped ZnO Nanorods by STM and STS

2008 ◽  
Vol 8 (12) ◽  
pp. 6598-6602 ◽  
Author(s):  
A. González-Carrazco ◽  
M. Herrera-Zaldívar ◽  
U. Pal
Keyword(s):  
Point Defect ◽  
Defect Formation ◽  
Zno Nanorods ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Zno Nanostructures ◽  
Tunneling Microscopy ◽  
Donor And Acceptor ◽  
Heavily Doped ◽  
Doped Zno

The effect of indium doping on the point defect formation in ZnO nanostructures is studied by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) techniques. While the incorporation of a donor dopant like indium should increase the n-type conductivity of ZnO nanostructures, it has been found that formation of VZn native acceptors in heavily doped ZnO nanostructures produces self-compensation effect, creating acceptor states in their band gap. Presence of both donor and acceptor states in heavily indium doped ZnO nanostructures are probed and identified. The mechanism of formation of such donor and acceptor states is discussed.

Defect Formation by Single Ion Impacts on Highly Oriented Pyrolytic Graphite Observed by Scanning Tunneling Microscopy

1994 ◽  
Vol 354 ◽  
Author(s):  
K. P. Reimann ◽  
W. Bolse ◽  
U. Geyer ◽  
G. Von minnigerode ◽  
K. P. Lieb
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Defect Formation ◽  
Pyrolytic Graphite ◽  
High Mobility ◽  
Incident Beam ◽  
Scanning Tunneling ◽  
Angle Of Incidence ◽  
Highly Oriented Pyrolytic Graphite ◽  
Tunneling Microscopy ◽  
Lattice Planes

Abstract(0001) surfaces of highly oriented pyrolytic graphite (HOPG) were irradiated at 77K with 132Xe+ ions at energies between 50 keV and 900 keV. The ion fluences ranged between 1011 ions/cm2 and 1015 ions/cm2. Scanning tunneling microscopy (STM) was applied to image the irradiation induced defects at the surfaces. In case of orthogonal incidence and small ion fluence each incident ion induces one single hillock at the surface. These hillocks have typical lateral diameters of 2 nm and heights of several à. In many cases measurements of the hillocks with atomic resolution show disordered atomic arrangements. The hillocks are interpreted as the local volume expansion due to surface-near self-interstitials generated in the collision cascades of the ions. The high mobility of these interstitials parallel to the (0001) planes leads to a formation of interstitial clusters which cause the larger hillocks. Irradiation at an angle of incidence of 75° with respect to the surface normal effects a higher density of hillocks due to the higher number of recoils stopped in the uppermost lattice planes. The hillocks are arranged in chains which are aligned in the direction of the incident beam. Each of these chains marks a single collision cascade.

scholarly journals Order–disorder phase transition of the subsurface cation vacancy reconstruction on Fe3O4(001)

2020 ◽  
Vol 22 (16) ◽  
pp. 8336-8343 ◽  
Author(s):  
Björn Arndt ◽  
Barbara A. J. Lechner ◽  
Alexander Bourgund ◽  
Elin Grånäs ◽  
Marcus Creutzburg ◽  
...  
Keyword(s):  
Phase Transition ◽  
Scanning Tunneling Microscopy ◽  
Surface Defect ◽  
Cation Vacancy ◽  
Scanning Tunneling ◽  
X Ray Diffraction ◽  
Tunneling Microscopy ◽  
X Ray ◽  
Disorder Phase Transition

Magnetite surface defect dynamics followed by fast scanning tunneling microscopy and surface X-ray diffraction.

Investigation of surface defect states in CeO2-y nanocrystals by Scanning−tunneling microscopy/spectroscopy and ellipsometry

2014 ◽  
Vol 116 (23) ◽  
pp. 234305 ◽  
Author(s):  
Marko Radović ◽  
Bojan Stojadinović ◽  
Nataša Tomić ◽  
Aleksandar Golubović ◽  
Branko Matović ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Surface Defect ◽  
Scanning Tunneling ◽  
Defect States ◽  
Tunneling Microscopy

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

Roughness measurements of nonlinear optical polymer films by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 22-23
Author(s):  
I. H. Musselman ◽  
R.-T. Chen ◽  
P. E. Russell
Keyword(s):  
Surface Roughness ◽  
Scanning Tunneling Microscopy ◽  
Nonlinear Optical ◽  
Polymer Surface ◽  
Light Extinction ◽  
Scanning Tunneling ◽  
Silicon Substrates ◽  
Tunneling Microscopy ◽  
Optical Polymer ◽  
Total Light

Scanning tunneling microscopy (STM) has been used to characterize the surface roughness of nonlinear optical (NLO) polymers. A review of STM of polymer surfaces is included in this volume. The NLO polymers are instrumental in the development of electrooptical waveguide devices, the most fundamental of which is the modulator. The most common modulator design is the Mach Zehnder interferometer, in which the input light is split into two legs and then recombined into a common output within the two dimensional waveguide. A π phase retardation, resulting in total light extinction at the output of the interferometer, can be achieved by changing the refractive index of one leg with respect to the other using the electrooptic effect. For best device performance, it is essential that the NLO polymer exhibit minimal surface roughness in order to reduce light scattering. Scanning tunneling microscopy, with its high lateral and vertical resolution, is capable of quantifying the NLO polymer surface roughness induced by processing. Results are presented below in which STM was used to measure the surface roughness of films produced by spin-coating NLO-active polymers onto silicon substrates.

Practical applications of scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 18-19
Author(s):  
D. R. Denley
Keyword(s):  
High Resolution ◽  
Scanning Tunneling Microscopy ◽  
Quantitative Information ◽  
Digital Data ◽  
Scanning Tunneling ◽  
Ambient Atmosphere ◽  
Tunneling Microscopy ◽  
Clear Trend ◽  
Practical Applications ◽  
Promising Tool

Scanning tunneling microscopy (STM) has recently been introduced as a promising tool for analyzing surface atomic structure. We have used STM for its extremely high resolution (especially the direction normal to surfaces) and its ability for imaging in ambient atmosphere. We have examined surfaces of metals, semiconductors, and molecules deposited on these materials to achieve atomic resolution in favorable cases.When the high resolution capability is coupled with digital data acquisition, it is simple to get quantitative information on surface texture. This is illustrated for the measurement of surface roughness of evaporated gold films as a function of deposition temperature and annealing time in Figure 1. These results show a clear trend for which the roughness, as well as the experimental deviance of the roughness is found to be minimal for evaporation at 300°C. It is also possible to contrast different measures of roughness.

Scanning tunneling microscopy of polymers: A status report

1989 ◽  
Vol 47 ◽  
pp. 330-331
Author(s):  
P.E. Russell ◽  
I.H. Musselman
Keyword(s):  
High Resolution ◽  
Scanning Tunneling Microscopy ◽  
Sample Surface ◽  
Atomic Scale ◽  
Constant Current ◽  
Scanning Tunneling ◽  
Status Report ◽  
Tunneling Microscopy ◽  
Research Issues ◽  
Wide Range

Scanning tunneling microscopy (STM) has evolved rapidly in the past few years. Major developments have occurred in instrumentation, theory, and in a wide range of applications. In this paper, an overview of the application of STM and related techniques to polymers will be given, followed by a discussion of current research issues and prospects for future developments. The application of STM to polymers can be conveniently divided into the following subject areas: atomic scale imaging of uncoated polymer structures; topographic imaging and metrology of man-made polymer structures; and modification of polymer structures. Since many polymers are poor electrical conductors and hence unsuitable for use as a tunneling electrode, the related atomic force microscopy (AFM) technique which is capable of imaging both conductors and insulators has also been applied to polymers.The STM is well known for its high resolution capabilities in the x, y and z axes (Å in x andy and sub-Å in z). In addition to high resolution capabilities, the STM technique provides true three dimensional information in the constant current mode. In this mode, the STM tip is held at a fixed tunneling current (and a fixed bias voltage) and hence a fixed height above the sample surface while scanning across the sample surface.

Scanning Tunneling Microscopy of Amorphous Carbon Films

1990 ◽  
Vol 48 (1) ◽  
pp. 318-319
Author(s):  
Mircea Fotino ◽  
D.C. Parks
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Amorphous Carbon ◽  
Carbon Films ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Amorphous Carbon Films ◽  
Image Optimization ◽  
Step Procedure ◽  
Stm Images

In the last few years scanning tunneling microscopy (STM) has made it possible and easily accessible to visualize surfaces of conducting specimens at the atomic scale. Such performance allows the detailed characterization of surface morphology in an increasing spectrum of applications in a wide variety of fields. Because the basic imaging process in STM differs fundamentally from its equivalent in other well-established microscopies, good understanding of the imaging mechanism in STM enables one to grasp the correct information content in STM images. It thus appears appropriate to explore by STM the structure of amorphous carbon films because they are used in many applications, in particular in the investigation of delicate biological specimens that may be altered through the preparation procedures.All STM images in the present study were obtained with the commercial instrument Nanoscope II (Digital Instruments, Inc., Santa Barbara, California). Since the importance of the scanning tip for image optimization and artifact reduction cannot be sufficiently emphasized, as stressed by early analyses of STM image formation, great attention has been directed toward adopting the most satisfactory tip geometry. The tips used here consisted either of mechanically sheared Pt/Ir wire (90:10, 0.010" diameter) or of etched W wire (0.030" diameter). The latter were eventually preferred after a two-step procedure for etching in NaOH was found to produce routinely tips with one or more short whiskers that are essentially rigid, uniform and sharp (Fig. 1) . Under these circumstances, atomic-resolution images of cleaved highly-ordered pyro-lytic graphite (HOPG) were reproducibly and readily attained as a standard criterion for easily recognizable and satisfactory performance (Fig. 2).

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