The effect of chemical polishing on the interface structure and electrical property of Au/Cd0.9Zn0.1Te contact

Abstract

The interface structures between Au electrode and Cd0.9Zn0.1Te wafer with different surface treatments are studied by means of transmission electron microscopy. Before the preparation of the Au film, atomic force microscopy and scanning electron microscopy are employed to investigate the surface morphology and elemental concentration before and after the chemical polishing process. It is found that an amorphous layer with the thickness of approximately 5 nm exists at the interface area for the only mechanical polished samples. As the chemical polishing process goes on, the interfaces become flatter and smoother. A thinner lattice mismatch layer instead of the amorphous layer after the chemical polishing process is found between Au and Cd0.9Zn0.1Te. The formation mechanism for the amorphous layer is considered to be the large lattice mismatch between Au and matrix. Furthermore, current–voltage (I–V) measurement is also carried out to investigate the relationship between the interface structure and electrical properties. The ohmic contact coefficient is calculated to increase from 0.4609 to 1.0904 after 4 min chemical polishing corresponding to the I–V test. It is indicated that the charges become easier to move across the interface, which has no amorphous layer, due to the weaker blocking effect to the charges for the thinner and ordered interface region.