Soli6 State Communications, Vol. 73, No. I, pp. 29-30, 1 9 9 0 . 0038-i098/9053.00+.00 Printed In Great Britain. Pergamon Press plc ON THE INTERFACE TRAPS IN GaAs Au-REFRACTORY BARRIERS A.Christou I - E.Evangelou 2 - G.Giakoumakis 2 - G.Papaioannou 3 (I) Naval Research Laboratory Washington, D.C. 20375, U.S.A. (2) Physics Department - University of Ioannina P.O.Box 1186 - 451 10 Ioannina - Greece (3) Physics Department - University of Athens Solonos 104 - 106 80 Athens - Greece (Received by S. Amelinckx - October 3rd, 1989) The defects induced by Au-refractory Schottky contacts have been studied using DLTS techniques. The TiPt-Au metal- lization was found to induce near the semiconductor surface a trap of 0.32eV activation energy. This trap was compared with other traps induced by other refractory metals and/or by the deposition method. Gold-refractory type Schottky barriers are important for the GaAs technology (self-aligned gates, circuits' stability at high temperatures etc). Recentlyl,2 it has been found that, although Ti/Pt/Au metallizations are superior in terms of the thermal stabilit~ they form TiPt and Ti3Pt phases at 150oc which accelerate the electromigration formation at current densities as low as 104 A/cm 2. On the other hand refractory metallizations in general result in dislocations generated in the GaAs due to differential thermal expansion and to interactions during the accelerated bias testing3. Process-induced defects also affect GaAs device perfor- mance and reliability, if interface and bulk traps are introduced during device fabrication. It has been shown that the low energy sputtering deposition or the electron beam evaporation 5 of Schottky contacts on GaAs, which is the case of TiPt-Au 6, introduces damage in the GaAs thus degrading the device performance. In the present investigation, usin~ Deep Level Transient Spectroscopy (DLTS~ we have measured the energy level of the interface states in TiPt-Au Schottky bar- riers to Si-doped n-GaAs. The devices under test were in the form of beam-lead Schottky diodes and prior to DLTS they have been characterized by C-V measu- rements.~he dqping level was found to be uniform (8.1016cm -J) and the capacitance constant in the temperature range of 80K to 300K. Figure 1 shows typical DLTS spectra for two reverse bias levels. In each spectrum only one negative peak was observed which shifted to lower tempera- tures when the reverse bias was decreased The activation energy 6E and the capture cross-sectlon o determined from the Arrhenlus plot (shown in figure 2) were 0.37e0.02eV and 4.10-18cm 2 respectively, F- e r- 29 T T 10FF i AC - - ~ %=-5v %=-1V r I I 100 200 300 Ternperafu re (K) Figure 1: DLTS spectra of the Schottky barriers under different bias level. I I i I I I I -11 " . .... EB5 "', .,., ., o ,, ...... E/16 ~ O """ "% %" 4: ..~ ... - .... B %*%% %,%', ~ "~. -1: %.%. ".. O <O''-.. %'%'%. .%" -.% %'% %., %'. %.% ~, % % ~- -14 %% ~'" I I I 1 I I I 4.4 4.8 4.8 5.0 IO00/T(I<') Figure 2: Arrhenius plot for theSchottky barriers studied and for traps known from the literature. This paper, ..... Nel and Auret 5 ..... Martin et al 9 ..... Christou et alI0