Enhancing the external quantum efficiency of Schottky barrier photodetectors through thin copper films

Silicon-based Schottky barrier photodetectors (SBPDs) are a cost-effective alternative to compound semiconductor-based photodetectors by extending the silicon's photodetection range to the near-infrared (NIR) region. However, SBPDs still suffer from low quantum yield due to poor absorption in a metal layer and low emission efficiency of hot electrons. This study investigates the use of thin copper (Cu) films as a means of improving the performance of SBPDs operating in the NIR region. Our results show that thin-film Cu SBPDs present a higher external quantum efficiency (EQE) compared to other metal SBPDs due to their low Schottky barrier height and long mean free path. Notably, at a bias of -3 V, the thinnest Cu SBPDs exhibit an EQE of the order of 1% at 1510 nm.