Attenuation Length of Hot Electrons in Gold

The attenuation length $L_P$ of hot electrons which are 0.95 eV above the Fermi level in Au is measured photoelectrically to be about 350 Å in Au films on both smooth cleaved Si and chemically cleaned Si. This result disagrees with that of Crowell, Spitzer, Howarth, and LaBate, who found $L_P\approx 740$ Å in Au films on rough cleaved Si. However, that value was calculated using the optical absorption of Au on glass, which was assumed to be the same as on Si. The absorption of Au films on Si is presented and used to correct the data of Crowell et al., giving $L_P\approx 332$ Å, in good agreement with the present measurements. Sze, Moll, and Sugano have reported $L_P\approx 700$ Å in Au; this high value appears to be caused by a different condition of the Si surface. Measurements of Au film resistivity versus thickness are presented which show that the films are nearly perfect and indicate that the $L_P$ in imperfection-free Au is $\approx 380$ Å.