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DS: Dünne Schichten

DS 24: Poster presentation

DS 24.28: Poster

Dienstag, 28. März 2006, 15:00–17:30, P2

Fabrication of ohmic Cr/Au contacts on top of cubic Boron Nitride thin films — •H. Yin, H.-G. Boyen, and P. Ziemann — Abteilung Festkörperphysik, Universität Ulm, 89069 Ulm

Cubic boron nitride (c-BN) is a superhard material with a hardness just second to diamond. In addition to many other attractive properties, c-BN also promises interesting applications as a high temperature electronics material due to its wide band gap (about 6eV), good thermal conductivity and good transmittance over a large spectral range from UV to visible. In this context, it is important to note that c-BN, unlike diamond films, can be doped both n- and p-type [1]. To arrive at such applications, however, high quality samples with a low level of defects are necessary. A significant step towards this goal has been achieved recently by the epitaxial growth of single phase c-BN films on top of diamond substrates applying ion beam-assisted deposition (IBAD) [2].

A further necessary intermediate step for electronic applications, however, is the preparation of corresponding ohmic electrical contacts on top of c-BN films. In the present work, Pulsed Laser Deposition (PLD) and Evaporation were tested to fabricate Cr/Au contacts through a mask on top of c-BN films. It turned out that evaporated films had to be additionally ion bombarded at room temperature with 300 keV Ar+ ions to guarantee mechanical stability whereas the PLD films were stable without further bombardment. The resulting I-V characteristics for both types of contacts exhibit the required ohmic behavior.

[1] O. Mishima et.al., Appl Phys Lett 53 (1988) 962 [2] XW Zhang et.al., Nature Materials 4 (2003) 312