Improved thermal stability CrB2 contacts on ZnO

Abstract

Most common contact metals show low thermal stabilities on ZnO and there is a clear need for more thermally stable metallization. The formation of rectifying contacts on n-type bulk single crystal ZnO using CrB2 was studied using current-voltage, scanning electron microscopy (SEM) and Auger Electron Spectroscopy (AES) measurements. When a single Au overlayer was used to reduce the metal sheet resistance, the contacts were ohmic for all annealing conditions. Under these conditions, both Zn and O were observed to outdiffuse from the ZnO. When a bilayer of Pt/Au was used on top of the CrB2 layers, rectifying contacts with barrier heights of ∼0.4eV were obtained after annealing at 600°C, although at this condition the contact showed a reacted appearance and AES showed the onset of intermixing of the metallization. At higher anneal temperatures (700°C) the contact metallization showed blistering and loss of adhesion. © 2005 The Japan Society of Applied Physics.