Effects of hydrogen ion implantation dose on physical and electrical properties of Ge-on-insulator layers fabricated by the smart-cut process

Abstract

We experimentally evaluate the influence of a hydrogen ion implantation (I/I) dose on the physical and electrical properties of Ge-on-insulator (GOI) films fabricated by the smart-cut process with the two doses of 1 × 1017 cm-2 and 4 × 1016 cm-2. It is found that thermal annealing is effective in improving the crystallinity of the GOI layers and that the defect-less GOI layers can be realized under the optimized annealing temperature of 550 °C, irrespective of the I/I dose. However, the reduction of Hall hole mobility is observed in GOI substrates fabricated with higher I/I dose condition. This mobility reduction is not observed for GOI p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) under the back-gate operation. On the other hand, n-channel MOSFETs fabricated on the smart-cut GOI substrates with As-doped S/D junctions are found to exhibit the higher effective electron mobility for the low I/I dose than that for the high I/I dose. As a result, it can be concluded that the high H+ I/I dose of 1 × 1017 cm-2 causes the degradation in the mobility of smart-cut GOI substrates and that the choice of the hydrogen I/I dose is important in the fabrication of GOI wafers for MOSFET applications.