Magnonics as an emerging nanotechnology offers functionalities beyond current semiconductor technology. Spin waves used in cellular nonlinear networks are expected to speed up technologically, demanding tasks such as image processing and speech recognition at low power consumption. However, efficient coupling to microelectronics poses a vital challenge. Previously developed techniques for spin-wave excitation (for example, by using parametric pumping in a cavity) may not allow for the relevant downscaling or provide only individual point-like sources. Here we demonstrate that a grating coupler of periodically nanostructured magnets provokes multidirectional emission of short-wavelength spin waves with giantly enhanced amplitude compared with a bare microwave antenna. Exploring the dependence on ferromagnetic materials, lattice constants and the applied magnetic field, we find the magnonic grating coupler to be more versatile compared with gratings in photonics and plasmonics. Our results allow one to convert, in particular, straight microwave antennas into omnidirectional emitters for short-wavelength spin waves, which are key to cellular nonlinear networks and integrated magnonics.

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We present a detailed study on incomplete ionization (i.i.) of aluminum acceptors in highly aluminum-doped p(+) silicon formed by alloying from screen-printed Al pastes. We apply electrochemical capacitance-voltage (ECV) and secondary ion mass spectrometry (SIMS) measurements to detect the Al doping profiles and discuss key aspects necessary for a precise determination of the profiles. The excellent accordance of ECV- and SIMS-measured acceptor profile curves allows for the accurate investigation of Al acceptor ionization. We review the physics of i.i. and verify a simple quantitative model for incomplete Al acceptor ionization by comparing measured and calculated sheet-resistances of Al-doped p(+) Si surfaces. We thus show that the electrically active Al doping concentration is nearly two times lower than the total Al concentration, so that i.i. of Al acceptors has to be considered for the correct description of highly Al-doped p(+) Si regions. Therefore, our results allow for an improved quantitative analysis of n- and p-type silicon solar cells with Al-alloyed p(+) rear emitter or back surface field, respectively

Aluminum oxide (AlOx) is currently under intensive investigation for use in surface passivation schemes in solar cells. AlOx films contain negative charges and therefore generate an accumulation layer on p-type silicon surfaces, which is very favorable for the rear side of p-type silicon solar cells as well as the p+-emitter at the front side of n-type silicon solar cells. However, it has been reported that quality of an interfacial silicon sub-oxide layer (SiOx), which is usually observed during deposition of AlOx on Silicon, strongly impacts the silicon/AlOx interface passivation properties [1]. The present work demonstrates that a convenient way to control the interface is to form thin wet chemical oxides of high quality prior to the deposition of AlOx/a-SiNx:H stacks by the plasma enhanced chemical vapor deposition (PECVD).