Ge/Si quantum dots thin film solar cells

Abstract

Thin film p-i-n solar cells (SCs) with 30 bilayers undoped or p-type self-assembled Ge/Si quantum dots (QDs) were fabricated on n+-Si(001) substrates by ultrahigh vacuum chemical vapor deposition. Compared with the SCs without Ge QDs, the external quantum efficiency in infrared region and the short-circuit current densities of the SCs with Ge QDs increased. However, their open-circuit voltages and efficiencies decreased. The open circuit voltages of p-type Ge/Si QDs SCs recovered significantly at low temperature, which was due to the suppression of recombination centers and longer carrier lifetime.