Regensburg 2013 – scientific programme
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O: Fachverband Oberflächenphysik
O 13: Focus Session: Crystalline n-type semiconducting oxides - SnO2, Ga2O3, and In2O3 for novel devices (jointly with HL)
O 13.7: Talk
Monday, March 11, 2013, 17:30–17:45, H2
Schottky contacts on β-Ga2O3 thin films grown by pulsed laser deposition — •Daniel Splith, Stefan Müller, Holger von Wenckstern, and Marius Grundmann — Universität Leipzig, Semiconductor Physics Group, Institut für Experimentelle Physik II, Leipzig, Germany
A promising oxide semiconductor for high power electronics and transparent optoelectronic devices is β-gallium oxide (Ga2O3) with a band gap of about 4.9 eV. We have investigated the preparation and the properties of Schottky contacts (SCs) on Ga2O3 thin films. The thin films were grown from a Ga2O3 target with 1% SiO2 on c-sapphire substrates using pulsed-laser deposition at an oxygen pressure of 10−3 mbar. The ohmic contacts were fabricated by thermal evaporation of Ti and Al as reported in [1]. Subsequently, we prepared SCs by normal and reactive DC sputtering of metals like Nb, W or Cu. The I−V characteristics of such SCs showed rectification ratios up to 8 orders of magnitude for some of the Nb contacts. The dominant current transport mechanism is thermionic emission. From fits we determined ideality factors n down to 1.15 for the best W contacts and barrier heights ΦB up to 1.2 eV for the best Cu contacts. Temperature dependent I−V measurements yielded a linear dependence of ΦB and 1/n−1 on the inverse temperature in accordance to the theory of thermionic emission in the presence of a laterally inhomogeneous barrier. E. g. the mean barrier height ΦB for the Cu contacts is determined to be 1.6 eV with a standard deviation σΦ of 0.17 eV.
[1] E. G. Villora et al., Appl. Phys. Lett. 92, 202118 (2008)