Germanium possesses higher electron and hole mobilities than silicon. There is a big leap, however, between these basic material parameters and implementation for high-performance microelectronics. Here we discuss some of the major issues for Ge metal oxide semiconductor field effect transistors ͑MOSFETs͒. Substrate options are overviewed. A dislocation reduction anneal Ͼ800°C decreases threading dislocation densities for Ge-on-Si wafers 10-fold to 10 7 cm −2 ; however, only a 2 times reduction in junction leakage is observed and no benefit is seen in on-state current. Ge wet etch rates are reported in a variety of acidic, basic, oxidizing, and organic solutions, and modifications of the RCA clean suitable for Ge are discussed. Thin, strained epi-Si is examined as a passivation of the Ge/gate dielectric interface, with an optimized thickness found at ϳ6 monolayers. Dopant species are overviewed. P and As halos are compared, with better short channel control observed for As. Area leakage currents are presented for pϩ/n diodes, with the n-doping level varied over the range relevant for pMOS. Germanide options are discussed, with NiGe showing the most promise. A defect mode for NiGe is reported, along with a fix involving two anneal steps. Finally, the benefit of an end-of-process H 2 anneal for device performance is shown.

We investigate ultrathin superconducting TiN films, which are very close to the localization threshold. Perpendicular magnetic field drives the films from the superconducting to an insulating state, with very high resistance. Further increase of the magnetic field leads to an exponential decay of the resistance towards a finite value. In the limit of low temperatures, the saturation value can be very accurately extrapolated to the universal quantum resistance h/e2. Our analysis suggests that at high magnetic fields a new ground state, distinct from the normal metallic state occurring above the superconducting transition temperature, is formed. A comparison with other studies on different materials indicates that the quantum metallic phase following the magnetic-field-induced insulating phase is a generic property of systems close to the disorder-driven superconductor-insulator transition.

Temperature-and magnetic-field dependent measurements of the resistance of ultrathin superconducting TiN films are presented. The analysis of the temperature dependence of the zero field resistance indicates an underlying insulating behavior, when the contribution of Aslamasov-Larkin fluctuations is taken into account. This demonstrates the possibility of coexistence of the superconducting and insulating phases and of a direct transition from the one to the other. The scaling behavior of magnetic field data is in accordance with a superconductor-insulator transition (SIT) driven by quantum phase fluctuations in two-dimensional superconductor. The temperature dependence of the isomagnetic resistance data on the high-field side of the SIT has been analyzed and the presence of an insulating phase is confirmed. A transition from the insulating to a metallic phase is found at high magnetic fields, where the zero-temperature asymptotic value of the resistance being equal to h/e 2 .PACS numbers: 74.25. -q, 71.30.+h, 74.40.+k The interplay between superconductivity and localization is a phenomenon of fundamental interest, and the question of the nature of superconductivity and its evolution in two-dimensional disordered systems and a perpendicular magnetic field continues to receive a great deal of theoretical and experimental attention. Twodimensional systems are of special interest as two is the lower critical dimensions for both localization and superconductivity. Two ground states are expected to exist for bosons at T = 0: a superconductor with long-range phase coherence and an insulator in which the quantum mechanical correlated phase is disjointed. The zerotemperature superconductor-insulator transition (SIT) is driven purely by quantum fluctuations and is an example of a quantum phase transition [1]. The superconducting phase is considered to be a condensate of Cooper pairs with localized vortices, and the insulating phase is a condensate of vortices with localized Cooper pairs. Between these two states there is the only metallic phase point, and this metal has a bosonic nature as well. The theoretical description based on this assumption was suggested in [2]. At finite temperatures, a quantum phase transition is influenced by the thermal fluctuations, and according to the theory, (i) the film resistance R near the magnetic-field-induced SIT at low temperature T in the vicinity of the critical field B c is a function of one scaling variable δ = (B − B c )/T 1/νz , with the critical exponents ν and z being constants of order of unity, and (ii) at the transition point, the film resistance is of the order h/(2e) 2 ≈ 6.5 kΩ (the quantum resistance for Cooper pairs). Although much work has been done, and in many systems the scaling relations hold [3,4,5,6,7,8], the magnetic-field-induced SIT in disordered films remains a controversial subject, especially concerning the insulating phase and the bosonic conduction at B > B c . There is experimental evidence [7] that, despite the magnetoresistance being nonmonotonic, ...

F Fi ib br re e t ty yp pe es s iin n s sk ke el le et ta al l m mu us sc cl le es s o of f c ch hr ro on ni ic c o ob bs st tr ru uc ct ti iv ve e p pu ul lm mo on na ar ry y d di is se ea as se e p pa at ti ie en nt ts s r re el la at te ed d t to o r re es sp pi ir ra at to or ry y f fu un nc ct ti io on n a an nd d e ex xe er rc ci is se e t to ol le er ra an nc ce e A group of 22 COPD patients and 10 healthy control subjects were studied. In COPD patients, vital capacity (VC) and forced expiratory volume in one second (FEV1) were reduced to 79% and 51%, respectively. Diffusion indices (transfer factor of the lung for carbon monoxide (TL,CO) and carbon monoxide transfer coefficient (KCO)) were also reduced. Arterial oxygen tension (Pa,O 2 ) was normal or slightly altered. A maximal exercise test was performed and anaerobic threshold was calculated. Muscle samples from vastus lateralis were obtained by needle biopsy. Myosin heavy chain (MHC) and light chain (MLC) isoforms were separated by gel electrophoresis and quantified by densitometry. MHC isoforms were considered as molecular markers of fibre types.The proportion of the fast MHC-2B isoform was increased in COPD patients. TL,CO, KCO, VC and FEV1 were positively correlated with slow MHC isoform content. TL,CO and KCO were also negatively correlated with the content of the fast MHC-2B isoform. No correlation was found between exercise parameters and MHC isoform composition. The co-ordinated expression between MHC and MLC isoforms was altered in COPD patients.We conclude that reduced oxygen availability, probably in combination with muscle disuse, may determine muscle alterations in chronic obstructive pulmonary disease patients. The altered correlations between myosin heavy chain and light chain isoforms suggest that co-ordinated protein expression is lost in chronic obstructive pulmonary disease muscles. Eur Respir J 1997; 10: 2853-2860 Patients with chronic obstructive pulmonary disease (COPD) are characterized by poor quality of life and various degrees of limitation in their daily activity, mainly due to breathlessness. They are often self-limiting their level of activity into a downward spiral leading to further inactivity and muscle deconditioning. Exercise tolerance of COPD patients is determined by the level of ventilation that they can reach. Even at a rather low work rate the increase in ventilatory response and blood lactate concentration are higher than in normal subjects.Rehabilitation of COPD patients involves general exercise reconditioning. This is suggested as the best approach to the rehabilitation of COPD patients, and is usually performed by training large muscles of the lower and, less frequently, upper limbs [1]. The mechanisms underlying the improvement of the performance after general training in COPD subjects are still unclear.There is evidence that skeletal muscle function and structure are altered in COPD patients. Contractile strength is reduced [2] and energetic and oxidative metabolism are impaired [3][4][5]. Fibre-type compos...

We have investigated diffusion and activation of boron implanted with 6 keV energy to a maximum concentration of 8.0×1020atoms∕cm3 in crystalline germanium (c-germanium) and preamorphized germanium, employing rapid thermal annealing in the range of 400–600 °C. As-implanted boron profiles in preamorphized germanium are shallower than the ones in c-germanium due to channeling suppression. While boron diffusion is not observed either in c-germanium or during the germanium regrowth from amorphous state, the boron activation level achieved from the two starting phases is significantly different. A boron activation level of 2.4×1020atoms∕cm3 has been found in regrown germanium, while a level of only 1.2×1019atoms∕cm3 is observed in c-germanium. Remarkably, there is no evidence of any residual extended defectivity at the original crystalline/amorphous interface, when preamorphization is performed.