Quenching Effects in Scanning Tunneling Microscopy Studies of Epitaxial Growth

1999 ◽  
Vol 583 ◽  
Author(s):  
G. R. Bell
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Epitaxial Growth ◽  
Molecular Beam ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Molecular Beam Epitaxial ◽  
Rapid Quench ◽  
Molecular Beam Epitaxial Growth

AbstractThe experimental aspects of rapid-quench scanning tunneling microscopy are discussed. In particular, the effects of sample quenching are investigated in atomic-scale studies of the molecular beam epitaxial growth of GaAs. Implications for the study of the heteroepitaxial system InAs-GaAs are discussed.

scholarly journals Surface Reconstruction during Molecular Beam Epitaxial Growth of GaN (0001)

1998 ◽  
Vol 3 ◽  
Author(s):  
A. R. Smith ◽  
V. Ramachandran ◽  
R. M. Feenstra ◽  
D. W. Greve ◽  
A. Ptak ◽  
...  
Keyword(s):  
Molecular Beam ◽  
High Energy ◽  
Nitrogen Plasma ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Plasma Sources ◽  
Molecular Beam Epitaxial ◽  
Homoepitaxial Growth ◽  
Surface Reconstructions ◽  
Molecular Beam Epitaxial Growth

Surface reconstructions during homoepitaxial growth of GaN (0001) are studied using reflection high-energy electron diffraction and scanning tunneling microscopy. In agreement with previous workers, a distinct transition from rough to smooth morphology is seen as a function of Ga to N ratio during growth. However, in contrast to some prior reports, no evidence for a 2×2 reconstruction during GaN growth is observed. Observations have been made using four different nitrogen plasma sources, with similar results in each case. A 2×2 structure of the surface can be obtained, but only during nitridation of the surface in the absence of a Ga flux.

Cross-Sectional Scanning Tunneling Microscopy of Semiconductor Heterostructures

MRS Bulletin ◽  
1997 ◽  
Vol 22 (8) ◽  
pp. 22-26 ◽  
Author(s):  
Edward T. Yu
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Electronic Properties ◽  
Epitaxial Growth ◽  
Material Properties ◽  
Semiconductor Heterostructures ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Nanometer Scale ◽  
Tunneling Microscopy ◽  
Cross Sectional

As characteristic dimensions in semiconductor devices continue to shrink and as advanced heterostructure devices increase in prominence, the ability to characterize structure and electronic properties in semiconductor materials and device structures at the atomic to nanometer scales has come to be of outstanding and immediate importance. Phenomena such as atomic-scale roughness of heterojunction interfaces, compositional ordering in semiconductor alloys, discreteness and spatial distribution of dopant atoms, and formation of self-assembled nanoscale structures can exert a profound influence on material properties and device behavior. The relationships between atomic-scale structure, epitaxial growth or processing conditions, and ultimately material properties and device behavior must be understood for realization and effective optimization of a wide range of semiconductor heterostructure and nanoscale devices.Cross-sectional scanning tunneling microscopy (STM) has emerged as a unique and powerful tool in the study of atomic-scale properties in III-V compound semiconductor heterostructures and of nanometer-scale structure and electronic properties in Si micro-electronic devices, offering unique capabilities for characterization that in conjunction with a variety of other, complementary experimental methods are providing new and important insights into material and device properties at the atomic to nanometer scale. In this article, we describe the basic experimental techniques involved in cross-sectional STM and give a few representative applications from our work that illustrate the ability, using cross-sectional STM in conjunction with other experimental techniques, to probe atomic-scale features in the structure of semiconductor heterojunctions and to correlate these features with epitaxial-growth conditions and device behavior.

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).

Molecular-beam-epitaxial growth of Ga1−xInxSb on GaAs substrates

1997 ◽  
Vol 175-176 ◽  
pp. 883-887 ◽  
Author(s):  
J.H. Roslund ◽  
O. Zsebők ◽  
G. Swenson ◽  
T.G. Andersson
Keyword(s):  
Epitaxial Growth ◽  
Molecular Beam ◽  
Molecular Beam Epitaxial ◽  
Gaas Substrates ◽  
Molecular Beam Epitaxial Growth
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