K. M. Beauchamp

In situ formation of superconducting YBa2Cu3O7−x thin films using pure ozone vapor oxidation

Superconducting YBa2Cu3O7−x thin films have been prepared by coevaporation using an ozone vapor jet as an oxygen source. Films exhibiting zero resistance at 82 K have been fabricated in situ under high vacuum conditions using substrate temperatures of 700 °C without a post‐evaporation anneal in oxygen. This process has implications for in situ measurements of fully superconducting surfaces using a variety of probes as well as for the fabrication of devices and structures whose properties are dependent on surfaces and interfaces.

In situ growth of DyBa2Cu3O7−x thin films by molecular beam epitaxy

Films of DyBa2Cu3O7−x with transition temperatures as high as 89 K and with nominal thicknesses down to 35 A have been grown in situ using molecular beam epitaxy employing ozone as a source of reactive oxygen. The process has been successful with a variety of substrates including SrTiO3(100), SrTiO3(110), LaAlO3(100), MgO(100), and yttria‐stabilized zirconia. The films could be imaged with a scanning tunneling microscope at 4.2 K, indicating a conducting surface even at low temperatures.

High-temperature superconducting microbolometer

A superconducting microbolometer employing a DyBaCuO film deposited upon a silicon microstructure was found to have a responsivity of 800 V/W at 89 K and a response time of 1 ms.

In situ growth of DyBa sub 2 Cu sub 3 O sub 7 minus x thin films by molecular beam epitaxy

Films of DyBa2Cu3O7−x with transition temperatures as high as 89 K and with nominal thicknesses down to 35 A have been grown in situ using molecular beam epitaxy employing ozone as a source of reactive oxygen. The process has been successful with a variety of substrates including SrTiO3(100), SrTiO3(110), LaAlO3(100), MgO(100), and yttria‐stabilized zirconia. The films could be imaged with a scanning tunneling microscope at 4.2 K, indicating a conducting surface even at low temperatures.

Fabrication of high-Tc superconductors using ozone-assisted molecular beam epitaxy

Abstract Ozone-assisted molecular beam epitaxy (MBE) has been developed for growing high-Tc superconducting films. It involves the co-evaporation of their elemental constituents together with the use of ozone as a source of reactive oxygen. The advantage of using ozone over other forms of reactive oxygen is that it is stable enough to be prepared and delivered to the substrate in a very pure form using very simple apparatus, providing a well-characterized flow of oxidizing gas. Using ozone, a post-deposition anneal is not needed to produce films with high transition temperatures, and growth can be carried out at relatively low system pressures. As a consequence, the surface analysis using reflection high energy electron diffraction is possible during film growth. Recent refinements of ozone-assisted MBE directed at the YBa2Cu3O7-σ family of films are described here. The results indicate that this technique is very competitive for growing the highest quality superconducting films and should be ideal for fabricating structures.

Barrier technology for DyBa/sub 2/Cu/sub 3/O/sub 7-x/ junctions and related structures

Layered structures which include the high-temperature superconductor DyBa/sub 2/Cu/sub 3/O/sub 7-x/ have been fabricated using molecular beam epitaxy with ozone as the activated oxygen source. A c-axis-oriented DyBa/sub 2/Cu/sub 3/O/sub 7-x/ thin film with a T/sub c/ of 74 K has been grown on a layer of the rare earth sesquioxide Dy/sub 2/O/sub 3/ on a

Natural buffer layer in DyBa2Cu3O7−x films grown on Si by molecular beam epitaxy

Growth of a natural buffer layer has been observed for DyBa2Cu3O7−x films grown on Si substrates. The best DyBa2Cu3O7−x film, grown by molecular beam epitaxy with ozone as a source of activated oxygen, was 2300‐A thick, highly c‐axis oriented, and had a resistive‐transition onset at 90 K and zero resistance by 70 K. The natural buffer layer, which grew at the interface of the DyBa2Cu3O7−x film and the Si substrate, consisted of Si, Ba, and O. Transmission electron microscopy on this film revealed a 150‐A amorphous layer, whereas Auger electron spectroscopy depth profiling showed 400 A of chemical interdiffusion.

Natural buffer layer in DyBa sub 2 Cu sub 3 O sub 7 minus x films grown on Si by molecular beam epitaxy

Growth of a natural buffer layer has been observed for DyBa2Cu3O7−x films grown on Si substrates. The best DyBa2Cu3O7−x film, grown by molecular beam epitaxy with ozone as a source of activated oxygen, was 2300‐A thick, highly c‐axis oriented, and had a resistive‐transition onset at 90 K and zero resistance by 70 K. The natural buffer layer, which grew at the interface of the DyBa2Cu3O7−x film and the Si substrate, consisted of Si, Ba, and O. Transmission electron microscopy on this film revealed a 150‐A amorphous layer, whereas Auger electron spectroscopy depth profiling showed 400 A of chemical interdiffusion.

Onset superconductivity in ultrathin DyBa2Cu3O7 films

The superconductor-insulator transition has been explored in the low temperature limit using ultra thin DyBa2Cu3O7 c-axis oriented films prepared by molecular beam epitaxy. The results are remarkably similar to those obtained for amorphous Bi films deposited onto amorphous Ge at low temperatures.

Low temperature scanning tunneling spectroscopy of a DyBa2Cu3O7−x film

A superconducting film of DyBa 2 Cu 3 O 7−x was examined below 30 K with a scanning tunneling spectroscopy, i.e. scanning tunneling microscope (STM) images and tunneling data were obtained over the same area. Images were observed and some I-Vs showed charging effects.