With the demand for improved performance in microfabricated devices, the necessity to apply greater electric fields and voltages becomes evident. When operating in vacuum, the voltage is typically limited by surface flashover forming along the surfac
e of a dielectric. By modifying the fabrication process we have discovered it is possible to more than double the flashover voltage. Our finding has significant impact on the realization of next-generation micro- and nano-fabricated devices and for the fabrication of on-chip ion trap arrays for the realization of scalable ion quantum technology.
We investigate the spin-polarization of the ferromagnetic semiconductor (Ga,Mn)As by point contact Andreev reflection spectroscopy. The conductance spectra are analyzed using a recent theoretical model that accounts for momentum- and spin-dependent s
cattering at the interface. This allows us to fit the data without resorting, as in the case of the standard spin-dependent Blonder-Tinkham-Klapwijk (BTK) model, to an effective temperature or a statistical distribution of superconducting gaps. We find a transport polarization PC{approx}57%, in considerably better agreement with the k{cdot}p kinetic-exchange model of (Ga,Mn)As, than the significantly larger estimates inferred from the BTK model. The temperature dependence of the conductance spectra is fully analyzed.
