Effects of an Ion Bombardment on the Characteristics of a Metal/n-GaAs Tunnel Contact

Abstract

Gallium arsenide surfaces have been submitted to low‐energy ion bombardment. Metal/n‐GaAs tunnel contacts realized on the surfaces prepared in this manner present features which depend greatly on the ion energy. At very low energy (50 eV) gas ions provide a ``cleaning'' of the interface and yield tunnel characteristics which are essentially identical to those of a vacuum‐cleaved analogous contact. This technique may be used to define the origin of tunneling anomalies. Higher‐energy bombardments (100–150 eV) lead to strong changes of the tunnel properties which can be summarized as a large resistance increase in spite of a strong barrier lowering and the appearance of inelastic processes. A model based on the creation of structural defects accounts qualitatively for all of the observed phenomena. Tunneling represents, therefore, a promising technique in the study of very‐low‐energy ion bombardments.