Electronic structures of Zn1−x_{1-x}Cox_xO using photoemission and x-ray absorption spectroscopy

Electronic structures of Zn$_{1-x}$Co$_x$O have been investigated using photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). The Co 3d states are found to lie near the top of the O $2p$ valence band, with a peak around $\sim 3$ eV binding energy. The Co $2p$ XAS spectrum provides evidence that the Co ions in Zn$_{1-x}$Co$_{x}$O are in the divalent Co$^{2+}$ ($d^7$) states under the tetrahedral symmetry. Our finding indicates that the properly substituted Co ions for Zn sites will not produce the diluted ferromagnetic semiconductor property.Comment: 3 pages, 2 figure

Mix-and-match compatibility in asymmetric system markets

This paper shows that the private incentive for mix-and-match compatibility in system markets diverges from the social planner's incentive if competing suppliers are asymmetric in production cost or product quality. There can be too much or too little compatibility when the market is served by fully integrated system suppliers. Also, the market outcome involves socially too much incompatibility in the form of exclusive technological alliances when the market is composed of independent component suppliers. These results contrast with the standard one obtained in the symmetric setup and shed new light on public policy towards compatibility, technological alliances, and bundling practices in system markets