Quantum dot superlattice structure for high efficiency solar cells utilizing a bio-template and damage-free neutral beam etching

Silicon (Si) quantum dot (QD) superlattice structures are promising candidates for all-Silicon tandem solar cells. An original top-down process involving a bio-template etching mask and damage-free neutral beam etching has been developed in order to fabricate a sub-10-nm highly ordered and dense two-dimensional (2D) array (one layer) of Si nanodisks (Si-ND) with a silicon carbide (SiC) interlayer. The Si-ND 2D array with SiC interlayer had an extremely high optical absorption coefficient and high carrier transport due to the formation of a wide miniband. As a result, high efficiency solar cells with an open-circuit voltage of 0.556 V, short-circuit current of 31.3 mA/cm², fill factor of 72%, and conversion efficiency of 12.6% were fabricated for the first time.