Characterization of LPE Grown HgCdTe by Ion Scattering Spectrometry PDF Download
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Author: W. L. Baun
Publisher:
ISBN:
Category :
Languages : en
Pages : 29
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Book Description
Results are shown here for low energy ion scattering spectrometry (ISS) experiments on mercury cadmium telluride (HCT) grown by liquid phase epitaxy (LPE) on CdTe substrates. By proper etching of the substrates and control of epitaxial growth conditions, surfaces of the zinc blend structure may be obtained in which 111 faces have a top layer of cadmium and mercury (A sites) or of tellurium (B sites). Ion scattering experiments at low energies (500 V or less) on epitaxial HCT show only A or B sites. However, when the helium or neon ion beam potenntial is raised to values conventionally used (1500-2500 V), then energy losses from both A and B atoms are observed. At these higher energies the ions sputter or displace the outer atoms or tunnel through to interact with atoms in the second layer. Spectra obtained at these higher energies show interesting fine structure which suggest that energy losses are occurring in multiple collisions and nonbinary scattering. Scattered ion yield curves, which for some elements, show oscillatory fine structure, are dramatically different for A and B surfaces. Even though these yield curves are very complicated because of the structure and number of elements, the fine structure may prove useful for further understanding of interaction of neighboring atoms. Yield curves along with low energy ion scattering spectra provide a unique method of analysis of the outermost atomic layer of epitaxial films.
Author: W. L. Baun
Publisher:
ISBN:
Category :
Languages : en
Pages : 29
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Book Description
Results are shown here for low energy ion scattering spectrometry (ISS) experiments on mercury cadmium telluride (HCT) grown by liquid phase epitaxy (LPE) on CdTe substrates. By proper etching of the substrates and control of epitaxial growth conditions, surfaces of the zinc blend structure may be obtained in which 111 faces have a top layer of cadmium and mercury (A sites) or of tellurium (B sites). Ion scattering experiments at low energies (500 V or less) on epitaxial HCT show only A or B sites. However, when the helium or neon ion beam potenntial is raised to values conventionally used (1500-2500 V), then energy losses from both A and B atoms are observed. At these higher energies the ions sputter or displace the outer atoms or tunnel through to interact with atoms in the second layer. Spectra obtained at these higher energies show interesting fine structure which suggest that energy losses are occurring in multiple collisions and nonbinary scattering. Scattered ion yield curves, which for some elements, show oscillatory fine structure, are dramatically different for A and B surfaces. Even though these yield curves are very complicated because of the structure and number of elements, the fine structure may prove useful for further understanding of interaction of neighboring atoms. Yield curves along with low energy ion scattering spectra provide a unique method of analysis of the outermost atomic layer of epitaxial films.
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Category : Aeronautics
Languages : en
Pages : 1134
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Category : Science
Languages : en
Pages : 152
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Category : Metallurgy
Languages : en
Pages : 1192
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Category : Physics
Languages : en
Pages : 1058
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Author:
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Category : Science
Languages : en
Pages : 1128
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Author: Wenfeng Zhao
Publisher:
ISBN:
Category : Infrared detectors
Languages : en
Pages : 104
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HgCdTe is the dominant material currently in use for infrared (IR) focal-plane-array (FPA) technology. In this dissertation, transmission electron microscopy (TEM) was used for the characterization of epitaxial HgCdTe epilayers and HgCdTe-based devices. The microstructure of CdTe surface passivation layers deposited either by hot-wall epitaxy (HWE) or molecular beam epitaxy (MBE) on HgCdTe heterostructures was evaluated. The as-deposited CdTe passivation layers were polycrystalline and columnar. The CdTe grains were larger and more irregular when deposited by HWE, whereas those deposited by MBE were generally well-textured with mostly vertical grain boundaries. Observations and measurements using several TEM techniques showed that the CdTe/HgCdTe interface became considerably more abrupt after annealing, and the crystallinity of the CdTe layer was also improved. The microstructure and compositional profiles of CdTe(211)B/ZnTe/Si(211) heterostructures grown by MBE was investigated. Many inclined {111}-type stacking faults were present throughout the thin ZnTe layer, terminating near the point of initiation of CdTe growth. A rotation angle of about 3.5° was observed between lattice planes of the Si substrate and the final CdTe epilayer. Lattice parameter measurement and elemental profiles indicated that some local intermixing of Zn and Cd had taken place. The average widths of the ZnTe layer and the (Cd, Zn)Te transition region were found to be roughly 6.5 nm and 3.5 nm, respectively. Initial observations of CdTe(211)B/GaAs(211) heterostructures indicated much reduced defect densities near the vicinity of the substrate and within the CdTe epilayers. HgCdTe epilayers grown on CdTe(211)B/GaAs(211) composite substrate were generally of high quality, despite the presence of precipitates at the HgCdTe/CdTe interface. The microstructure of HgCdSe thin films grown by MBE on ZnTe/Si(112) and GaSb(112) substrates were investigated. The quality of the HgCdSe growth was dependent on the growth temperature and materials flux, independent of the substrate. The materials grown at 100°C were generally of high quality, while those grown at 140°C had {111}-type stacking defects and high dislocation densities. For epitaxial growth of HgCdSe on GaSb substrates, better preparation of the GaSb buffer layer will be essential in order to ensure that high-quality HgCdSe can be grown.
Author: W. Murray Bullis
Publisher: American Institute of Physics
ISBN:
Category : Science
Languages : en
Pages : 760
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Market: Those in government, industry, and academia interested in state-of-the-art knowledge on semiconductor characterization for research, development, and manufacturing. Based on papers given at an International Nist Workshop in January 1995, Semiconductor Characterization covers the unique characterization requirements of both silicon IC development and manufacturing, and compound semiconductor materials, devices, and manufacturing. Additional sections discuss technology trends and future requirements for compound semiconductor applications. Also highlighted are recent developments in characterization, including in- situ, in-FAB, and off-line analysis methods. The book provides a concise, effective portrayal of industry needs and problems in the important specialty of metrology for semiconductor technology.
Author: National Institute of Standards and Technology (U.S.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 1162
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Category : Electrical engineering
Languages : en
Pages : 2304
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