Synthesis and microwave properties of TI2Ba2CaCu2O8 superconducting films grown by MOCVD

Abstract

We report on the synthesis, structural and electrical characterization of high quality Tl2Ba2Ca1Cu2O8 (Tl-2212) superconducting films. The samples have been grown ex-situ on 10 × 10 mm 2 LaAlO3 (100) substrates by a combined approach of metal-organic chemical vapor deposition (MOCVD) and thallium vapor diffusion. The morphological and compositional nature of the c-axis oriented films has been investigated by SEM and X-ray analyses. Typical values of Tc = 104 K and Jc = 0.5 MA/cm 2 at 77 K have been measured. Microwave measurements have been performed at f = 87 GHz inserting the film in a copper cavity and at f = 1.5 GHz on patterned samples using a microstrip resonator technique. A penetration depth λ(0) = 400 nm is evaluated by fitting the microwave data with phenomenological equations. The minimum value of the surface resistance Rs measured at 4.2 K is 60 µΩ and 6 mΩ at 1.5 GHz and 87 GHz respectively. The microwave data are described in the context of a modified two fluid model. An evaluation of the temperature dependence of the scattering rate has been performed through the simultaneous measurement of the surface resistance and the penetration depth.

A metal-organic chemical vapor deposition approach to double-sided Tl2Ba2Ca1Cu2O8superconducting films on LaAlO3(100) substrates

“…of temperature shows a residual term R res # 10 mV for the side 2, while for the side 1 the R res term is about one order of magnitude higher. The former R res value is comparable to the surface resistance values measured on SS Tl-2212 film, 24 and when scaled for the usual quadratic frequency law, it is even better than results reported by Willemsen et al for SS films (R s,min y 50 mV at 3.7 GHz). 6 On the basis of the presented results, DS Tl-2212 films grown using MOCVD are very promising for the development of passive microwave planar devices for telecommunication applications.…”

Dual mode cross slotted filter realized with double-sided Tl2Ba2CaCu2O8films grown by MOCVD

“…where t is the sample thickness and λ the penetration depth. Typical measurements are reported in figure 4, yielding a value of the surface resistance R s (20 GHz) ≈ 4 m at 80 K. This value, properly scaled in frequency within the conventional two-fluid model, is consistent with measurements performed on single-sided films at 87 GHz [6]. Moreover, it is also in agreement with values reported [12] on rf-sputtered samples (R s = 2 m at 10 GHz).…”

“…Several techniques with a two-step post-annealing process have been previously adopted, such as magnetron [2], laser ablation [3] or off-axis sputtering [4,5]. We have also previously reported on the realization of Tl-2212 single-sided films grown by a combined approach of metal-organic chemical vapour deposition (MOCVD) and thallium vapour diffusion [6]. This technique has the potential advantage of being a very reliable and reproducible method for the fast production of films with a high degree of uniformity over large areas for both thickness and composition.…”