Germanium oxynitride gate dielectrics formed by plasma nitridation of ultrathin thermal oxides on Ge(100)

Abstract

Germanium oxynitride (GeON) gate dielectrics with surface nitrogen-rich layers were fabricated by plasma nitridation of thermally grown oxides (GeO2) on Ge(100). Insulating features of ultrathin GeO2 layers of around 2-nm-thick were found to improve with plasma treatment, in which leakage current was drastically reduced to over four orders of magnitude. Consequently, Au/GeON/Ge capacitors of an equivalent oxide thickness down to 1.7 nm were achieved while keeping sufficient leakage reduction merit. The minimum interface state density values of GeON/Ge structures as low as 3×1011 cm−2 eV−1 were obtained for both the lower and upper halves of the bandgap without any postnitridation treatments. These results were discussed based on the effects of plasma nitridation on a degraded GeO2 surface for recovering its electrical properties by creating stable nitride layers.