Improved charge transport through Si based multiple quantum wells with substoichiometric SiOx barrier layers.

The vertical charge transport through Si/SiO_x multiple quantum wells (QWs) is investigated. Upon thermal annealing, segregation of excess Si from the SiO_x layers leads to the formation of highly conductive pathways between Si grains from adjacent QWs separated by ultrathin silicon oxide barriers with barrier heights of 0.53–0.65 eV. Compared to stoichiometric Si/SiO₂ layer stacks, conductivity is increased by up to ten orders of magnitude, which opens the way to an efficient charge carrier extraction in photovoltaic systems with distinct quantum confinement. [ABSTRACT FROM AUTHOR]