ACCURATE MEASUREMENT OF ATOMIC-BEAM FLUX BY PSEUDO-DOUBLE-BEAM ATOMIC-ABSORPTION SPECTROSCOPY FOR GROWTH OF THIN-FILM OXIDE SUPERCONDUCTORS

We report the use of pseudo-double-beam atomic absorption spectroscopy to make very accurate (0.1%-1%) measurements of the beam flux from Knudsen effusion cells in a molecular beam epitaxy system. This system has been used to grow Bi-Sr-Ca-Cu-O-based superconducting thin films and heterostructures in an atomic-layer-by-layer fashion. The resulting material displays excellent crystallographic and transport properties. Atomic absorption measurement of beam fluxes may also be of benefit for other materials systems, such as InGaAs/InP.