Functional Oxides for Photoneuromorphic Engineering: Toward a Solar Brain

Abstract

New device concepts and new computing principles are needed to balance our ever-growing appetite for data and information with the realization of the goals of increased energy efficiency, reduction in CO 2 emissions and the circular economy. Neuromorphic or synaptic electronics is an emerging field of research aiming to overcome the current computer's Von-Neumann bottleneck by building artificial neuronal systems to mimic the extremely energy efficient biological synapses. The introduction of photovoltaic and/or photonic aspects into these neuromorphic architectures will produce self-powered adaptive electronics but may also open up new possibilities in artificial neuroscience, artificial neural communications, sensing and machine learning which would enable, in turn, a new era for computational systems owing to the possibility of attaining high bandwidths with much reduced power consumption. This perspective is focused on recent progress in the implementation of functional oxide thinfilms into photovoltaic and neuromorphic applications towards the envisioned goal of selfpowered photovoltaic neuromorphic systems or a solar brain.

Nanoscale self-organisation in Mott insulators: a richness in disguise

“…8. We note that the interface between two domains, i.e., two strain vectors ǫ 2,i and ǫ 2,j , i = j, is directed along the third vector, ǫ 2,k , k = i, j, in accordance with the curl-free condition (12), and with the experimental data presented in Sec. 2.…”

Giant bulk photovoltaic effect in solar cell architectures with ultra-wide bandgap Ga2O3 transparent conducting electrodes

“…For any photovoltaic device in general the choice of the electrodes (and/or buffer contact-layers) is critically important (the literature on this topic is huge -see e.g. [51] for a review for transparent conducting oxides and oxide buffers). So far, a change of electrodes in thin-film ferroelectric photovoltaic devices has been correlated with improvements in either photo-current or photo-voltage (or both).…”

“…In thin-film photovoltaics, in general, the low doped (intrinsic) absorber or the barrier extraction layers (either n-type or p-type) conductivities do not change. Either, a n-i-p or p-i-n configuration establishes the direction of the photocurrent by engineering the band-offset alignment [51]. The photo-current flows to the outer electrodes when electrons shift to lower energies while the holes shift to higher energies (respect to the vacuum level).…”

p-Type Ultrawide-Band-Gap Spinel ZnGa2O4: New Perspectives for Energy Electronics

“…The emerging transparent semiconductor oxide (TSO) technology based on ultra-wide bandgap oxides holds the promise of extending many energy and optoelectronic applications further into the deep ultraviolet range, overpassing the conventional wide bandgap TSO's near ultraviolet limit (~3.5 eV) (e.g. ZnO, SnO2 or In2O3) [13][14][15] . Nevertheless, to exploit the full potential of any emerging ultra-wide bandgap solid-state semiconductor technology for electronics, a good control (over several orders of magnitude) of the n-type and p-type conductivity should be attained.…”