The origin of Fermi-level (FL) depinning at TiN/Ge interfaces was studied using first-principles calculation. It was shown that FL pinning occurs at abrupt clean interfaces, while depinning occurs at interfaces with N-rich interface layers such as TiN 2 and Ge 3 N 4 , which is in good agreement with the experiments. By analyzing electronic structures, we found that the termination of interface Ge atoms by N atoms, i.e. the production of interface N-Ge bonds, is the key to realize FL depinning at TiN/Ge interfaces. The effects of missing N-Ge interface bonds were also discussed.

The control of Fermi-energy position at metal/Ge interface is one of issues to be overcome for developing next-generation Ge devices. In this work, at first, we study the Schottky barrier at various TiN/Ge interfaces by the first-principles calculation and show that the Fermi-level pinning occurs at clean TiN/Ge interface, while the pinning is broken, i.e., the depinning occurs, at N-rich TiN/Ge interface, in agreement with experiments. By analyzing electronic structures, we show that the appearance of N-rich interface layers such as TiN2 and Ge3N4 layers realizes the depinning. Next, we compare the depinning features at various metal/Ge interfaces and show that the termination of interface bonds of Ge eliminates the electronic freedom of gap states in interface Ge layers and promotes the depinning.

To clarify how the Fermi-level (FL) pinning changes by segregation, we artificially produced metal/X/Ge (001) interfaces with various segregation atoms X that terminate interface Ge atoms and calculate the Schottky barriers at these interfaces by the first-principles calculations. We found the chemical trend that the segregation of II-and III-family atoms lowers the FL position, while that of V-and VI-family atoms raises the FL position. It was shown that such trend reflects the electron transfer around the interface.

a), T. NISHIMOTO (b), s. HAYAsH13) (c), and s. NWUCHI (c)Magnetothermal oscillations in dilute Bi-Sb alloys are measured with dc methods in fields up to 22 kOe. The period of the oscillation agrees with that one obtained from the deHaas-van Alphen effect. A splitting of the peak is observed around 15 kOe and considered as the spin splitting of electrons. The spin-splitting factor 2 4 calculated from the present results shows some deviations from unity. The deviations are interpreted by assuming the effect of the other bands after Baraff. The variation of 24 with increasing Sb concentration seems to imply that the relative energies of the other bands a t the point L in the Brillouin zone "shrink" with regard to the centre of the gap.Magnetothermische Oszillationen werden fur verdiinnte Bi-Sb-Legierungen im magnetischen Feld bis 22 kOe gemessen. Die Periode der Oszillation stimmt gut mit experimentellen Ergebnissen des de Haas-van Alphen-Effekts iiberein. Das Maximum der magnetothermischen Oszillation bei 16 kOe zeigt jedoch eine Aufspaltung, die mit der Spin-Aufspaltung der Elektronen erkliirt wird. Der beobachtete Spin-Aufspaltungsfaktor 24 zeigt eine Abweichung von eins. Die Abweichung wird mit dem Effekt der anderen Biinder nach Baraff erkliirt. Unter Beachtung der h d e r u n g des Spin-Aufspaltungsfaktors mit der Sb-Konzentration wird die relative Energie der anderen Bander am Punkt L in der Brillouin-Zone beziiglich des Zentrums berechnet.