Figure 1

SEM images of the BNNPs and NPs on thin a-Si film and glass substrates. (a, d) Au MNPs on glass and thin a-Si film substrates, respectively (10-nm-thick Au film annealed at 600°C for 1 min). (b, e) Ag MNPs on glass and thin Si film substrates, respectively (8-nm-thick Ag film annealed at 400°C for 1 min). (c, f) Au-Ag BNNPs on glass and thin a-Si film substrates, respectively (10-nm-thick Au film annealed at 600°C for 1 min, followed by deposition of 8-nm-thick Ag film and annealing at 400°C for 1 min).