Effectiveness of SiGe Buffer Layers in Reducing Dark Currents of Ge-on-Si Photodetectors

The effectiveness of thin SiGe buffer layers in terminating threading dislocations and reducing photodiode dark current for Ge epitaxially grown on Si (001) has been investigated. The structural morphology of the films was studied by atomic force microscopy and transmission electron microscopy. The dark current of Ge on Si photodiodes can be reduced by over an order of magnitude by incorporating two different composition SiGe buffer layers. The origin of dark current and the effectiveness of thermal annealing the SiGe layers were also studied