Thickness dependence of J c (0) in MgB 2 films

Micro-SQUIDs based on MgB2nano-bridges for NEMS readout

“…Similarly for D2, with I c (4.2 K)≈0.8 mA and A=1.1×10 −11 cm 2 , we calculate J c ≈3.5×10 7 A cm −2 . The J c value of D2 sample results comparable to one obtained in references [4,5], whereas the D1 device shows a higher current density value, like that reported in [20].…”

MgB2thick films on three-dimensional structures fabricated by HPCVD

“…The J C (0) at 5 K for samples 1 to 4 were 1.4×10 5 , 3.8×10 5 , 5.1×10 5 , and 3.8×10 4 A•cm −2 respectively. These J C values are lower than those on single crystal Al 2 O 3 or SiC substrate [17]. As is shown in figure 3, the films we obtained have a lot of voids and gaps inside, which potentially affect the current carrying capacity of the films and lead to a decrease of J c .…”

“…From samples 2 and 3, at the optimum deposition position, an average thickness of 10 μm was measured. A deposition rate of 11.1 nm s −1 can be calculated, which is higher than that of conventional HPCVD [3,[16][17][18]. The deposition rate is determined by the pressure of Mg vapor and the flow rate of B 2 H 6 .…”

“…A variety of methods have been developed to fabricate MgB 2 films, including pulsed laser deposition [13], molecular beam epitaxy (MBE) [14], electron beam evaporation [15], and hybrid physical−chemical vapor deposition (HPCVD) [3]. Among these techniques, HPCVD seems to be the most effective way to fabricate high-performance MgB 2 films from several nanometers to dozens of micrometers thick [3,[16][17][18][19][20]. Most of the research on HPCVD has focused on planar surfaces, as planar MgB 2 films can be used in many applications like kinetic inductance detectors [21], superconducting quantum interference devices (SQUIDs) [5], and hot-electron bolometer mixers [22], etc.…”