Electrical properties of nanometer-sized Schottky contacts on n-GaAs and n-InP formed by in situ electrochemical process

The current transport characteristics of nanometer-sized Schottky contacts were investigated from theoretical and experimental viewpoints. A theoretic al calculation of the three dimensional (3D) potential distributions showed that the potential shape underneath the nano-Schottky contacts was conside rably modified by the surface Fermi level pinning on the air exposed free s urfaces, producing a saddle point in the potential. The curl ent-voltage (I -V) curves were strongly influenced by this saddle point potential and resu lted in nonlinear log I-V characteristics. Experimentally, the Pt nano-part icles were selectively formed using the in situ electrochemical process on n-type GaAs and n-type InP substrates patterned using electron-beam (EB) li thography. Their I-V measurements were carried out using an atomic force mi croscopy (AFM) system equipped with a conductive probe. The log I-V curves of the nano-Schottky contacts showed nonlinear characteristics with large n values of 1.96 for n-GaAs and 1.27 for n-InP and could be very well explai ned by the theoretical I-V curves considering the "environmental" Fermi lev el pinning.