Heteroepitaxial Ge on Si Using III-V Buffers

Mitigating the power concerns involved with the aggressive shrinking of silicon (Si) based complementary metal-oxide-semiconductor (CMOS) transistors requires the adoption of high-mobility, alternative materials such as Germanium (Ge). Although the use of Ge in bulk form is cost-prohibitive, creative methods such as the application of Ge on to Si substrate via a buffer layer "bridge" helps drive the feasibility of the use of Ge for novel, low-power applications using standard CMOS processes. This work explores the electrical and material characteristics of MOS capacitors fabricated on crystallographic Ge integrated on to Si substrate via AlAs/GaAs buffers. Electrical characteristics of different crystallographically oriented Ge integrated on AlAs/GaAs buffers and the tunability of a key device characteristic known as threshold voltage is demonstrated as well. Thus, this research demonstrates the feasibility of the use of Ge integrated on Si via AlAs/GaAs buffer layers for high-speed, low-power electronic devices.