Effects of Ambient Conditions in Thermal Treatment for Ge

Ge-MISFETs have attracted much attention as next generation MOSFETs because of their higher carrier mobility than Si-MOSFETs. However, it has been regarded as extremely difficult to form a gate stack structure with good quality because surfaces of Ge and the oxide films are very unstable thermally and chemically. Therefore, establishment of a surface passivation technique is one of the most important issues for realizing Ge-MISFETs. Although Ge-MIS structures that use GeON and high-k materials as the gate insulator, the interface trap density has been still high, compared with Si-MOS structures. Moreover, the measurement method of the interface trap density in the Ge-MIS structures has not been established yet. In this study, the influence of ambient conditions in Ge surface treatment was examined through the fabrication and electrical characterization of Ge-MIS capacitors