@article{WuBeckerWaagetal.1992, author = {Wu, Y. S. and Becker, Charles R. and Waag, A. and Bicknell-Tassius, R. N. and Landwehr, G.}, title = {Thermal effects on (100) CdZnTe substrates as studied by x-ray photoelectron spectroscopy and reflection high energy electron diffraction}, issn = {0003-6951}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-37801}, year = {1992}, abstract = {The influence of different CdZnTe substrate treatments prior to II-VI molecular beam epitaxial growth on surface stoichiometry, oxygen, and carbon contamination has been studied using x-ray photoelectron spectroscopy and reflection high energy electron diffraction. Heating the substrate at 300 °C can eliminate oxygen contamination, but cannot completely remove carbon from the surface. Heating at higher temperatures decreases the carbon contamination only slightly, while increasing the Zn-Cd ratio on the surface considerably. The magnitude of the latter effect is surprising and is crucial when one is using lattice matched CdZnTe (Zn 4\%) substrates.}, language = {en} } @article{BeckerWuWaagetal.1991, author = {Becker, Charles R. and Wu, Y. S. and Waag, A. and Kraus, M. M. and Landwehr, G.}, title = {The orientation independence of the CdTe-HgTe valence band offset as determined by x-ray photoelectron spectroscopy}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-30784}, year = {1991}, abstract = {No abstract available}, language = {en} } @article{EinfeldtHeinkeBehringeretal.1994, author = {Einfeldt, S. and Heinke, H. and Behringer, M. and Becker, Charles R. and Kurtz, E. and Hommel, D. and Landwehr, G.}, title = {The growth of HgSe by molecular beam epitaxy for ohmic contacts to p-ZnSe}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38001}, year = {1994}, abstract = {The structural properties of HgSe grown by molecular beam epitaxy (MBE) are investigated for different lattice mismatches to the substrate and various growth conditions. The growth rate is shown to depend strongly on the growth temperature above lOO°C as well as on the Hg/Se flux ratio. It has been found that the crystalline perfection and the electrical properties are mainly determined by the layer thickness, especially for the growth on highly lattice mismatched substrates. Changes in the surface morphology are related to growth parameters. Differences between the electrical behavior of MBE-grown and bulk HgSe are discussed. The electrical properties of HgSe contacts on p-ZnSe are investigated as a function of different annealing procedures.}, language = {en} } @article{BeckerHeRegnetetal.1993, author = {Becker, Charles R. and He, L. and Regnet, M. M. and Kraus, M.M. and Wu, Y. S. and Landwehr, G. and Zhang, X. F. and Zhang, H.}, title = {The growth and structure of short period (001) Hg\(_{1-x}\)Cd\(_x\)Te-HgTe superlattices}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-37858}, year = {1993}, abstract = {Molecular beam epitaxially grown short period (001) Hg\(_{1_x}\)Cd\(_x\)Te-HgTe superlattices have been systematically investigated. Several narrow well widths were chosen, e.g., 30, 35 and 40 {\AA}, and the barrier widths were varied between 24 and 90 {\AA} for a particular well width. Both the well width and the total period were determined directly by means of x-ray diffraction. The well width was determined by exploiting the high reflectivity from HgTe and the low reflectivity from CdTe for the (002) Bragg reflection. Knowing the well and barrier widths we have been able to set an upper limit on the average Cd concentration of the barriers, \(\overline x_b\), by annealing several superlattices and then measuring the composition of the resulting alloy. \(\overline x_b\) was shown to decrease exponentially with decreasing barrier width. The structure of a very short period superlattice, i.e., 31.4 {\AA}, was also investigated by transmission electron microscopy, corroborating the x-ray diffraction results.}, language = {en} } @article{WuBeckerWaagetal.1991, author = {Wu, Y. S. and Becker, Charles R. and Waag, A. and Bicknell-Tassius, R. N. and Landwehr, G.}, title = {The effects of laser illumination and high energy electrons on molecular-beam epitaxial growth of CdTe}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-30795}, year = {1991}, abstract = {We report the results of a detailed investigation on the Te-stabilized (2 x 1) and the Cdstabilized c( 2 X 2) surfaces of ( 100) CdTe substrates. The investigation demonstrates for the first time that both laser illumination and, to a greater extent, high-energy electron irradiation increase the Te desorption and reduce the Cd desorption from ( 100) CdTe surfaces. Thus it is possible by choosing the proper growth temperature and photon or electron fluxes to change the surface reconstruction from the normally Te-stabilized to a Cd-stabilized phase.}, language = {en} } @article{WuBeckerWaagetal.1993, author = {Wu, Y. S. and Becker, Charles R. and Waag, A. and von Schierstedt, K. and Bicknell-Tassius, R. N. and Landwehr, G.}, title = {Surface sublimation of zinc blende CdTe}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-37829}, year = {1993}, abstract = {The surface sublimation of Cd and Te atoms from the zinc blende (111)A CdTe surface has been investigated in detail by reflection high energy electron diffraction and x-ray photoelectron spectroscopy. These experiments verify that Te is much easier to evaporate than Cd. The experimental value for the Te activation energy from a Te stabilized (111)A CdTe surface is 1.41 ±0.1O eV, which is apparently inconsistent with recent theoretical results.}, language = {en} } @article{WuBeckerWaagetal.1993, author = {Wu, Y. S. and Becker, Charles R. and Waag, A. and Bicknell-Tassius, R. N. and Landwehr, G.}, title = {Removal of oxygen and reduction of carbon contamination on (100) Cd\(_{0.96}\)Zn\(_{0.04}\)Te}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38014}, year = {1993}, abstract = {No abstract available}, language = {en} } @article{WuBeckerWaagetal.1993, author = {Wu, Y. S. and Becker, Charles R. and Waag, A. and Schmiedl, R. and Einfeldt, S. and Landwehr, G.}, title = {Oxygen on the (100) CdTe surface}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-37869}, year = {1993}, abstract = {We have investigated oxygen on CdTe substrates by means of x-ray photoelectron spectroscopy (XPS) and reflection high-energy electron diffraction (RHEED). A Te oxide layer that was at least 15 A thick was found on the surface of as-delivered CdTe substrates that were mechanically polished. This oxide is not easily evaporated at temperatures lower than 350°C. Furthermore, heating in air, which further oxidizes the CdTe layer, should be avoided. Etching with HCI acid (15\% HCl) for at least 20 s and then rinsing with de-ionized water reduces the Te oxide layer on the surface down to 4\% of a monoatomic layer. However, according to XPS measurements of the 0 Is peak, 20\%-30\% of a monoatomic layer of oxygen remains on the surface, which can be eliminated by heating at temperatures ranging between 300 and 340 cC. The RHEED patterns for a molecular beam epitaxially (MBE)-grown CdTe film on a (lOO) CdTe substrate with approximately one monoatomic layer of oxidized Te on the surface lose the characteristics of the normal RHEED pattems for a MBE-grown CdTe film on an oxygen-free CdTe substrate.}, language = {en} } @article{ToenniesBacherForcheletal.1994, author = {T{\"o}nnies, D. and Bacher, G. and Forchel, Alfred and Waag, A. and Litz, Th. and Hommel, D. and Becker, Charles R. and Landwehr, G. and Heuken, M. and Scholl, M.}, title = {Optical study of interdiffusion in CdTe and ZnSe based quantum wells}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-37750}, year = {1994}, abstract = {No abstract available}, language = {en} } @article{HeBeckerBicknellTassiusetal.1993, author = {He, L. and Becker, Charles R. and Bicknell-Tassius, R. N. and Scholl, S. and Landwehr, G.}, title = {Molecular beam epitaxial growth of (100) Hg\(_{0.8}\)Cd\(_{0.2}\)Te on Cd\(_{0.96}\)Zn\(_{0.04}\)Te}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38044}, year = {1993}, abstract = {No abstract available}, language = {en} }