@article{RoeschAtzmuellerSchaacketal.1994, author = {R{\"o}sch, M. and Atzm{\"u}ller, R. and Schaack, G. and Becker, Charles R.}, title = {Resonant Raman scattering in a zero-gap semiconductor: Interference effects and deformation potentials at the E\(_1\) and E\(_1\) + \(\Delta_1\) gaps of HgTe}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38062}, year = {1994}, abstract = {No abstract available}, language = {en} } @article{ZhangBeckerZhangetal.1994, author = {Zhang, X. F. and Becker, Charles R. and Zhang, H. and He, L. and Landwehr, G.}, title = {Investigation of a short period (001) HgTe-Hg\(_{0.6}\)Cd\(_{0.4}\)Te superlattice by transmission electron microscopy}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38029}, year = {1994}, 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{SchikoraHausleitnerEinfeldtetal.1994, author = {Schikora, D. and Hausleitner, H. and Einfeldt, S. and Becker, Charles R. and Widmer, T. and Giftige, C. and Lischka, K. and von Ortenburg, M. and Landwehr, G.}, title = {Epitaxial overgrowth of II-VI compounds on patterned substrates}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-37985}, year = {1994}, abstract = {The selected area epitaxial overgrowth of narrow gap HgTe as well as wide gap CdTe and ZnTe on CdTe/GaAs substrates, which had been structured by dry etching techniques, has been investigated. A plasma etching process using a barrel reactor with CH\(_4\)-CH\(_2\) gases has been employed to prepare stripes with a width of about 1 μm with anisotropic as well as isotropic etching profiles. It has been found, that the selected area HgTe overgrowth takes place with a high local selectivity to the low index planes of the patterned surface. In contrast, the selected area overgrowth of the wide gap CdTe and ZnTe is controlled by anisotropic growth kinetics provided that the substrate temperature is not lower than 220°C and the starting surface consists of well developed low index crystallographic planes.}, 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} } @inproceedings{BoegeSchaeferShanjiaetal.1994, author = {Boege, P. and Sch{\"a}fer, H. and Shanjia, Xu and Xinzhang, Wu and Einfeldt, S. and Becker, Charles R. and Hommel, D. and Geick, R.}, title = {Improved conductivity-measurement of semiconductor epitaxial layers by means of the contactless microwave method}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-37763}, year = {1994}, abstract = {Measurements and calculations of the scattering-characteristics of stratified lossy dielectric blocks completely filling a waveguide cross section are presented. The method is used for contactless conductivity measurements of MBE-grown II-VI semiconductor layers.}, subject = {Millimeterwelle}, language = {en} } @article{XuShengGreineretal.1994, author = {Xu, Shanjia and Sheng, Xinqing and Greiner, P. and Becker, Charles R. and Geick, R.}, title = {High-order finite-element analysis of scattering properties of II-VI semiconductor materials}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-86283}, year = {1994}, abstract = {The sattering characteristics ot the n-VI semiconductors were analyzed by a method which combines the second-order finite-element method with the rigorous mode matching procedure. The method avolds the difficulty of solving the complex transcendental equation introduced in the multimode network method and calculates all the eigenvalues and eigenfunctions simultaneously which are needed for the mode matching treatment in the longitudinal direction. As a result, the whole solution procedure is significantly simplified. A comparison is given between the experimental data and the calculated results obtained with this analysis and tbe network method. Very good agreement has been achieved, the accuracy and efficiency of the present method are thus verified.}, subject = {Halbleiter}, language = {en} } @article{BeckerHeEinfeldtetal.1993, author = {Becker, Charles R. and He, L. and Einfeldt, S. and Wu, Y. S. and L{\´e}rondel, G. and Heinke, H. and Oehling, S. and Bicknell-Tassius, R. N. and Landwehr, G.}, title = {Molecular beam epitaxial growth and characterization of (100) HgSe on GaAs}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-50947}, year = {1993}, abstract = {In this paper, we present results on the first MBE growth of HgSe. The influence of the GaAs substrate temperature as well as the Hg and Se fluxes on the growth and the electrical properties has been investigated. It has been found that the growth rate is very low at substrate temperatures above 120°C. At 120°C and at lower temperatures, the growth rate is appreciably higher. The sticking coefficient of Se seems to depend inversely on the Hg/Se flux ratio. Epitaxial growth could be maintained at 70°C with Hg/Se flux ratios between lOO and ISO, and at 160°C between 280 and 450. The electron mobilities of these HgSe epilayers at room temperature decrease from a maximum value of 8.2 x 10^3 cm2 /V' s with increasing electron concentration. The concentration was found to be between 6xlO^17 and 1.6x10^19 cm- 3 at room temperature. Rocking curves from X-ray diffraction measurements of the better epilayers have a full width at half maximum of 5S0 arc sec.}, subject = {Physik}, language = {en} } @article{BeckerLatussekHeinkeetal.1993, author = {Becker, Charles, R. and Latussek, V. and Heinke, H. and Regnet, M. M. and Goschenhofer, F. and Einfeldt, S. and He, L. and Bangert, E. and Kraus, M. M. and Landwehr, G.}, title = {Molecular beam epitaxial growth and characterization of (001) Hg\(_{1-x}\) Cd\(_x\) Te-HgTe superlattices}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-50959}, year = {1993}, abstract = {The molecular beam epitaxially growth of (001) Hg\(_{1-x}\) Cd\(_z\) Te-HgTe superlattices has been systematically investigated. The well width as well as the period were determined directly by X-ray diffraction. This was accomphshed for the well width by exploiting the high reflectivity from HgTe and the low reflectivity from CdTe for the (002) Bragg reflection. Knowing the well and barrier thicknesses we have been able to set an upper limit on the aver~ge composition of the barriers, Xl, by annealing the superlattice and then measuring the composition of the. resultmg alloy. Xb was shown to decrease exponentially with decreasing barrier width. Xb is appreciably smaller m. narrow barriers due to the increased significance of interdiffusion in the Hg\(_{1-x}\)Cd\(_x\) Te/HgTe interface in narrow barriers. The experimentally determined optical absorption coefficient for these superlattices is compared WIth theoretical calculations. The absorption coefficient was determined from transmission and reflection spectra at 300, 77 and 5 K. Using the thickness and composition of the barriers and wells, and an interface width due to interdiffusion, the complex refractive index is calculated and compared with the experimental absorption coefficient. The envelope function method based on an 8 x 8 second order k . p band model was used to calculate the superlattice states. These results when inserted into Kubo's formula, yield the dynamic conductivity for interband transitions. The experimental and theoretical values for the absorption coefficient using no adjustable parameters are in good agreement for most of the investigated superlattices. Furthermore the agreement for the higher energetic interband transitions is much worse if values for the barrier composition, which are appreciably different than the experimentally determined values, are used. The infrared photoluminescence was investigated at temperatures from 4.2 to 300 K. Pronounced photoluminescence was observed for all superlattices in this temperature range.}, subject = {Physik}, language = {en} } @article{ShanjiaXinzhangBoegeetal.1993, author = {Shanjia, Xu and Xinzhang, Wu and Boege, P. and Sch{\"a}fer, H. and Becker, Charles R. and Geick, R.}, title = {Scattering characteristics of 3-D discontinuity consisting of semiconductor sample filled in waveguide with gaps}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-37964}, year = {1993}, abstract = {No abstract available}, language = {en} }