Effect Of Annealing On The Electronic Structure Of Auxpd1-X Thin Films On Silicon: Diffusion Of Si And Silicide Formation

AuxPd1-x alloys provide efficient hot-carrier generation in the near-infrared via direct interband transitions. When grown on silicon, they offer a route to ultrafast near-infrared photodetection. Before AuxPd1-x alloys can be successfully implemented in photodetector devices, it is essential to understand how processing temperature affects their electronic properties. Herein we study how alloy composition and annealing temperature, under UHV conditions, change the electronic properties of AuxPd1-x alloy films deposited on Si(1 00). We observed silicide formation at the surface of alloy films with high Au fraction (e.g., x > 0.9) at only 200 degrees C, whereas films with lower Au fraction (e.g., x 0.7) required temperatures up to 450 degrees C to form silicides. We attribute the increased temperature stability of the AuxPd1-x alloys with 30% Au to the higher negative heat of formation for these compositions and to the strong hybridization between Pd 4d and Au 5d states that may participate in the suppression of Si diffusion to the surface.