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Room temperature direct band gap emission from Ge p-i-n heterojunction photodiodes
2012, Kasper, E., Oehme, M., Arguirov, T., Werner, J., Kittler, M., Schulze, J.
Room temperature direct band gap emission is observed for Si-substrate-based Ge p-i-n heterojunction photodiode structures operated under forward bias. Comparisons of electroluminescence with photoluminescence spectra allow separating emission from intrinsic Ge (0.8 eV) and highly doped Ge (0.73 eV). Electroluminescence stems fromcarrier injection into the intrinsic layer, whereas photoluminescence originates from the highly n-doped top layer because the exciting visible laser wavelength is strongly absorbed in Ge. High doping levels led to an apparent band gap narrowing from carrier-impurity interaction. The emission shifts to higher wavelengths with increasing current level which is explained by device heating. The heterostructure layer sequence and the light emitting device are similar to earlier presented photodetectors. This is an important aspect for monolithic integration of silicon microelectronics and silicon photonics.
Promoters for Pd-catalyzed methoxycarbonylation of vinyl acetate
2012, Shuklov, I.A., Dubrovina, N.V., Schulze, J., Tietz, W., Kühlein, K., Börner, A.
A study on the influence of acidic and non-acidic promoters for Pd(PPh 3)-catalyzed methoxycarbonylation of vinyl acetate was conducted in order to find an efficient protocol for the synthesis of methyl O-acetyl lactate. Besides known promoters also some new catalytic systems were tested. Aluminium triflate is the most active additive.