Improvement of Electrical Properties of HfO2/Si0.73Ge0.27 Gate Stacks Through Selective Remote GeOx Scavenging

In this article, a selective remote GeO_x scavenging method is presented to reduce interface trap density (D_it) in HfO₂/Si_0.73Ge_0.27 gate stacks using an Al-rich Al_x O_y cap as the scavenging layer. The GeO_x scavenging process is driven by the formation energy gain between Al₂ O₃ and GeO₂ during postdeposition annealing (PDA). The Ni/HfO₂/Si_0.73 Ge_0.27 metal-oxide semiconductor (MOS) capacitors subjected to the selective remote GeO_x scavenging method demonstrate significant reductions in D_it. Through the optimization of cap thickness and PDA temperature, a GeO_x-free interfacial layer (IL) in the HfO₂/Si_0.73 Ge_0.27 gate-stack has been successfully achieved. Notably, the Si_0.73 Ge_0.27 device with GeO_x-free IL could achieve an excellent D_it value of 1.3 × 10¹¹ eV^-1 cm^-2.