Copper Schottky contacts to oxygen-plasma-treated n-type Ge

Using current-voltage (I–V) measurements, we investigated the effect of oxygen plasma treatment on the electrical properties of Cu/n-type Ge Schottky contacts. Compared to untreated n-Ge, oxygen plasma was found to produce a higher (lower) barrier height and a lower (higher) ideality factor at a plasma power of 100 W (250 W). Compared to untreated n-Ge, the series resistance was decreased at low plasma power and increased at high plasma power, which was associated with the removal of the native oxide layer and the induced defects near the Ge surface, respectively. The smaller variations in the electrical parameters for oxygen-plasma-treated n-Ge suggest that oxygen-plasma treatment improved the homogeneity of the Schottky barrier’s interface. Our results suggest that optimized oxygen plasma can be used as a pretreatment method before depositing a thin insulating layer.