Effect of thermal annealing in nitrogen on theI - VandC - Vcharacteristics of Cr - Ni - Co alloy/LEC n-GaAs Schottky diodes

The Schottky barrier height and ideality factor n of Cr - Ni - Co alloy Schottky contacts on an n-LEC GaAs substrate have been measured using current - voltage (I - V) and capacitance - voltage (C - V) techniques after different thermal annealings for 5 min in (temperature range from 300 to ). The values of and n for the forward I - V characteristics range from 0.65 and 1.001 eV at room temperature (RT) to 0.86 and 1.095 eV at . Thereby, the barrier height enhancement has been explained in terms of the presence of microclusters of one or more interface phases produced by reactions between the alloy and GaAs or the native oxide layer. The stability value of 1.010 for n from the RT to annealing has been ascribed to reduction of the native oxide layer on the GaAs surface by Cr in the alloy. The C - V relationship of the Cr - Ni - Co/n-GaAs Schottky diode at 1 MHz gives values of 0.68, 0.74 and 0.85 eV for at RT, and annealing temperatures respectively. The fact that the - V curves after annealing above show two linear regions separated by a transition segment has been attributed to the diffusion of Cr into GaAs during the thermal annealing process.