An improved Mo/n-GaAs contact by interposition of a thin Pd layer

The idea of limited reaction has been used to solve the adhesion and stability problems of Mo/n-GaAs and Pd/n-GaAs contacts. The structural and electrical properties of Mo/Pd/n-GaAs with different thicknesses of Pd layer, annealed from 300°C to 500°C for 30 min, were investigated. Adhesion of Mo to GaAs has been improved with the interposition of a thin Pd layer. With increasing Pd thickness, wider temperature ranges were achieved in which the contact showed rectifying Schottky behavior. The Schottky barrier heights were nearly constant below 300°C and then dropped sharply at 450°C, except for Mo(2000 Å)/Pd(200 Å)/n-GaAs diodes. The ideality factors converged to nearly unity at 300°C and then increased sharply from 300 to 500°C, except for Mo(2000 Å)/Pd(200 Å)/n-GaAs diodes, which maintained a nearly constant value of 1.34 from 400 to 500°C