PENETRATION DEPTH MEASUREMENTS OF SINGLE-CRYSTAL NBN FILMS AT MILLIMETER-WAVE REGION

The zero temperature penetration depth lambda(0) of single-crystal NbN thin films has been measured at 82 GHz using an open resonator. The N bN films used in this study have a (200) single-crystal structure and T-c and rho(20) (normal state resistivity at 20 K) are 16 K and 62 m O mega cm, respectively. lambda(0) was obtained by applying a least-squa res fit to the change of penetration depth using the BCS theory. We ob tain lambda(0)=194 nm, which shows good agreement with the calculated value from Tc,rho(20) and Delta(0). (C) 1996 American Institute of Phy sics.