LINKED MAGNETRON SPUTTERING AND PULSED-LASER DEPOSITION UHV CHAMBERS FOR THE PREPARATION OF EPITAXIAL METAL-METAL OXIDE MULTILAYERS

A UHV deposition system for the production of epitaxial oxide/metal he terostructures on single crystal ceramic substrates is described, The system has two novel features. The first is the use of linked, dedicat ed UHV sputtering and pulsed laser deposition chambers for the metal a nd oxide growth respectively, so as to maintain the cleanliness of the metal surface alter deposition. The second is the use of a pulsed oxy gen source during oxide growth to minimize damage of the metal layer b y oxidation during the growth of the oxide layer. This second issue is illustrated by the growth of magnesium oxide/niobium bilayers on sapp hire substrates. The magnesium oxide was grown under varying condition s of oxygen supply. A clean niobium film with net magnesium oxide over layer showed a resistance ratio of 76. if the magnesium oxide was grow n under UHV conditions (no extra oxygen supply) then the resistance ra tio of the niobium film was reduced to 26. Growth of the magnesium oxi de with synchronous 0.6 ms oxygen pulses (total ambient oxygen exposur e 121 Pa s) resulted in a niobium resistance ratio of 18. A similar ex posure to oxygen pulses alone (no magnesium oxide layer) reduced the n iobium resistance ratio to 1.2, Alternatively the magnesium oxide laye r could be grown in an argon ambient, with maintenance of the residual resistance ratio at 60 in 20 Pa of argon.