THERMAL-STABILITY OF CR-NI-CO ALLOY SCHOTTKY CONTACTS ON MBE N-GAAS

The thermal stability of the Schottky barrier height Phi(b) Of Cr-Ni-C O alloy Schottky contacts on an MBE n-GaAs substrate has been investig ated using current-voltage (I-V) and capacitance-voltage (C (-2)-V) te chniques after thermal annealing for 5 min in an N-2 atmosphere at sev eral temperatures in the 200-600 degrees range. It has been found that the value of Phi(b) (0.83 or 0.84 eV) remains constant up to 600 degr ees C in the forward I-V mode. Because of the presence of an interfaci al layer between the alloy contact and GaAs, an ideality factor value of 1.31 was obtained for as-deposited samples. This value decreases to 1.18 with increasing annealing temperature up to 400 degrees C. At an nealing temperatures above 400 degrees C, the ideality factor n starts to increase. This has been explained in terms of the presence of diff erent metallic-like phases produced by chemical reactions between the alloy and GaAs because of the annealing process. The Phi(b)(C-V) value s obtained from the reverse-bias C-2-V curves of the as-deposited and annealed diodes at 1 MHz are in the range 0.96-1.09 eV. The difference (0.13-0.26 eV) between Phi(b)(C-V) and the Phi(b)(l-V) is in close ag reement with values reported in literature.