Figure 4From: Nanostructured copper/porous silicon hybrid systems as efficient sound-emitting devicesPhoto-acoustic spectra. Photo-acoustic spectra of the Si wafer (Si), Si wafer after immersion in the Cu solution (Si + Cu), nanoPS layer (nanoPS), and nanoPS layer after Cu nanoparticle deposition (nanoPS + Cu). The photo-acoustic measurements were performed with a 785-nm wavelength laser.Back to article page