Current collection from different Si devices based on nanoscale Si-layered systems containing a new metamaterial for photovoltaics

摘要

Nanoscale Si-layered systems represent an attractive way to enlarge optical and electrical functions in Si optoelectronic, photonic and PV technology. Physical interactions transform the initial Si material to a new Si-based metamaterial. The device architecture also plays a role in specific nonlinear features. The newly observed behavior requires a better insight into understanding the mechanisms determining the macroscopic performance. We report here some specific electrical properties resulting from the complexity of the electron transport in different test structures designed and manufactured by us. One of the most important parameters concerns state of the device surface. Measurements have been carried out in different conditions of illumination (spectral composition, intensity, with/without optical bias), acquisition mode (duration of acquisition) and device polarization mode (photodiode, photovoltaic). Time-resolved current collection with stabilized voltages, as well as time-resolved voltage variation under stabilized currents, both made under light excitation, allowed observation of extremely long time constants