Münster 1997 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 40: Poster III
HL 40.91: Poster
Freitag, 21. März 1997, 11:00–14:00, Z
Schottky diodes of nitride forming metals on n–type GaN — •Michèle T. Hirsch, Kristin J. Duxstad, F. M. Ross, and E. E. Haller — Lawrence Berkeley National Laboratory and University of California at Berkeley 1 Cyclotron Rd., 94720, CA, Berkeley, USA
We report on Schottky barriers of nitride forming metals on n-type GaN. Titanium, which behaves rectifying as deposited on chemically prepared surfaces [1], however, acts as ohmic contact after 900 oC rapid thermal annealing (RTA) [2]. The formation of TiN has been proposed to be responsible for this changing behavior. We report on the effect of mild annealing (T<350oC) on Ti Schottky barriers, for which we observe effective barrier heights Φb0 increasing from below 200meV (as deposited) to 450meV (after 230oC anneal). Structural studies (Auger Electron Spectroscopy, TEM) suggest the formation of TiN at the interface, even at these low annealing temperatures. These results will be compared to studies of the barrier height and the thermal stability of Schottky contacts of other nitride forming metals as Ta, Mo or Zr. We discuss the observed barrier heights in terms of different models for barrier formation and phase formation at the interface and consider implications for possible mechanisms that explain ohmic behavior of RTAed Ti contacts.
[1] S. C. Binari et al. , Electron. Lett. 30, 909, (1994).
[2] Z. Fan, et al. , Appl. Phys. Lett. 68, 1003 (1996). Work supported by US DOE under contract DE-AC03-76SF00098.