Search

The n-type doping of AlGaAs with disilane (Si2H6) was investigated. To overcome the known disadvantages of the commonly used group III precursors, diethylaluminiumhydride-trimethylaminadduct (DEAlH-NMe3) as Al source and triethylgallium (TEGa) as Ga source were used. The dependence of the carrier concentration on the Si2H6partial pressure was studied. A weak dependence on the substrate orientation was found. Temperature dependent Hall measurements gave no indication to DX centers. With low frequency noise measurements a deep level with an activation energy of 0.27 eV was detected. The electrical properties gave a hint to H passivation of the DX center and an AlO complex acting as deep level. Superlattices were grown to find growth parameters for the growth of abrupt GaAsAlGaAs interfaces. As an application of the doping studies and optimization of the heterointerfaces, a two-dimensional electron gas structure was grown. A room temperature mobility of μ300= 5 300 cm2/V·s and at 77 K μ77= 52 000 cm2/V·s with a corresponding sheet carrier concentration of ns= 1 × 1012cm−2was achieved.

Krogman, W. M. & Iscan, M. Y., 1986: The human skeleton in forensic medicine. Second edition. Charles C. Thomas Publisher, Springfield; Perizonius, W. R. K. (ed.), 1988: Bones. Treasuries of human experience in time and space. Newsletter Dept. of Anthropo-Osteology, Rijksuniversiteit Utrecht. Vol. 1. E. J. Brill, Leiden; Tattersall, I., Delson, E. & van Couvering, J. (eds.), 1988: Encyclopedia of human evolution and prehistory. Garland Publishing, Inc., New York/London; Löther, R. (Hrsg.), 1988: Tiersozietäten und Menschengesellschaften. Philosophische und evolutionsbiologische Aspekte der Soziogenese. Reihe "Philosophie und Biowissenschaften"; Preuß, F., 1987: Der Aufbau des Menschlichen. Die Mitschöpfung der Lebewesen an ihrer Gestaltung. Verlag Paul Parey, Hamburg/Berlin; Collins, K.J. & Roberts, D.F. (eds.), 1988: Capacity for work in the tropics. Society for the Study of Human Biology Symposium Series 26. Cambridge University Press, Cambridge/New York/New Rochelle/Melboume/Sydney; Levitan, M., 1988: Textbook of Human Genetics. Third edition. Oxford University Press, Oxford/New York; Oliver, St.G. & Ward, J.M., 1988: Wörterbuch der Gentechnik. UTB 1478. Gustav Fischer Verlag, Stuttgart; Hirsch-Kauffmann, M. & Schweiger, M., 1987: Biologie für Mediziner, Pharmazeuten und Chemiker. Georg Thieme Verlag, Stuttgart/New York; Franke, H., 1987 : Hoch- und Höchstbetagte. Ursachen und Probleme des hohen Alters. Verständliche Wissenschaft, Bd. 118. Springer-Verlag, Berlin/Heidelberg/New York/London/Paris/Tokyo; Fiedler, H.J. & Rösler, H.J. (Hrg.), 1988: Spurenelemente in der Umwelt. Ferdinand Enke Verlag, Stuttgart; McGregor, A. (ed.), 1986: Evolution, Creative Intelligence and Intergroup Competition. The Mankind Quarterly, Monograph No. 3, Cliveden Press, Washington D.C.; Betzig, L. L., 1986: Despotism and differential reproduction. A Darwinian view of history. Aldine Publishing Company, New York and Walter de Gruyter & Co., Berlin; Moore, J. R., 1981: The Post-Darwinian Controversies. A study of tbe Protestant struggle to come to terms witb Darwin in Great Britain and America 1870-1 900. Cambridge University Press, Cambridge/London/New York/New Rochelle/Melbourne/Sydney; Stanley, St. M., 1987: Extinction. Scientific American Library. W. H. Freeman and Comp., Oxford. XII; Acta Historica Leopoldina Nr. 17, 1987: Das Kaiserliche Privileg der Leopoldina vom 7. August 1687. Herausgegeben zur Jahresversammlung 1987 vom Präsidum der Akademie. Deutsche Akademie der Naturforscher Leopoldina Halle (Saale); Fleischer, G., 1986: Dia-Vorträge. Planung, Gestaltung, Durchführung. Georg Thieme Verlag, Stuttgart/New York; Nei, M. & Koehn, R. K. (eds.), 1983: Evolution of genes and proteins. Blackwell Scientific Publications, Oxford, and Sinauer Associates, Inc., Sunderland (Mass.); Skinner, M. F. & Sperber, G. H., 1982: Atlas of Radiographs in Early Man. Alan R. Liss, Inc., New York; Lasker, G. W„ 1985: Surnames and genetic structure. Cambridge Studies in Biological Anthropology, Vol. 1. Cambridge University Press, Cambridge/London/New York/New Rochelle/Melbourne/Sydney; Cameron, N., 1984: The measurement of human growth. Croom Helm, London/Sydney; Ellyson, St. L. & Dovidio, J. F. (eds.), 1985, Power, dominance and nonverbal behavior. Springer-Verlag, Berlin/Heidelberg/New York/Tokyo; Campbell, B., 1985: Human ecology. Tbe story of our place in nature from prehistory to the present. Aldine Publishing Company, New York und Walter de Gruyter & Co., Berlin; Terrell, J., 1986: Prehistory in tbe Pacific Islands. A study of variation in language, customs and human biology. Cambridge University Press, Cambridge/London/New York/New Rochelle/Melbourne/Sydney; Delson, E. (ed.), 1985: Ancestors: The hard evidence. Proceedings of the Symposium held at the American Museum of Natural History April 6-10, 1984. Alan R. Liss, Inc., New York; Cattle, D. J. & Schwerin, K. H. (eds.), 1985: Food energy in tropical ecosystems. Gordon and Breach Science Publishers, New York/London/Paris/Montreux/Tokyo.

Müller-Hill, B., 1988: Murderous Science. Elimination by scientific selection of Jews, Gypsies, and others, Germany 1933—1945. Oxford University Press, Oxford/New York/Tokyo; Roychoudhury, A. K. & Nei, M., 1988: Human polymorphic genes. World distribution. Oxford University Press, Oxford/New York; Sperlich, D., 1988: Populationsgenetik. Grundlagen und experimentelle Ergebnisse. 2. völlig neubearb. und erg. Aufl. Gustav Fischer Verlag, Stuttgart/New York; Johnston, F. E. (ed.), 1987: Nutritional Anthropology. Alan R. Liss, lnc., New York; Betzig, L., Borgerhoff Mulder, M. & Turke, P. (eds.), 1988: Human reproductive behaviour. A Darwinian perspective. Cambridge University Press, Cambridge/New York/New Rochelle/Melbourne/Sydney;Junker, R. & Scherer, S. (Hg.), 1986: Entstehung und Geschichte der Lebewesen. Daten und Deutungen für den schulischen Bereich. Weyel Lehrmittelverlag, Gießen; Gravel, P. B. & Ridinger, R. B., 1988: Anthropological fieldwork. An annoted bibliograpby. Garland Publishing, Inc., New York/London; Man, Th. L. (ed.), 1988: Bibliographical directory of anhbropologists born before 1920. Compiled by Library-Anthropology Resource Group (LARG). Garland Publishing Inc., New York/London.

High-performance pseudomorphic InP/InxGa1-xAs/InP backside-doped split-channel heterostructure field-effect transistors (BDSCh-HFETs) with a strained undoped In0.75Ga0.25P Schottky-barrier enhancement layer are reported. Devices with mushroom-shaped gates (LG = 0.25 µm) demonstrated at 300 K maximum extrinsic transconductances of gm = 510 mS/mm and current cutoff frequencies of fT = 102 GHz coupled with off-state drain-source breakdown voltages of VDSbr= 10 V. At 18 GHz a unilateral power gain of 25.6 dB was measured, corresponding to fmax > 200 GHz.

High performance InP/In0.75Ga0.25As/InP pseudomorphic double heterojunction (DH) HEMTs with a gate length of 0.5 μm are reported. Both DC and RF characteristics of this new type of Al-free HEMT demonstrate its suitability for microwave applications.

The dinucleoside phosphorodithioate (VIII) may be used for the preparation of oligomers.