Hole mobility in strained Ge/relaxed SiGe with a High-k/metal gate stack

[摘要] The need for high speed and density in the modem semiconductor industry requires new channel materials and techniques for improved carrier transport and continuous scaling of the device dimensions. As a material for enhanced hole transport strained-Ge is implemented in this work. High-k dielectric and metal gate stack is used for improved electrostatic control, as an alternative to the unstable native oxides. The hole mobility of strained-Ge ring-FETs with and without Si cap and with A12 0 3/WN gate stack is investigated. The dependence of the mobility on the strained-Ge layer thickness and the silicon cap thickness is explored. Decrease of 13 % in the hole mobility is observed in the devices with thicker Ge channel suggesting partial relaxation of the strained-Ge. Removal of the Si cap results in almost 40 % decrease in hole mobility suggesting that the presence Si cap is required in realizing high mobility devices.

[发布机构] Massachusetts Institute of Technology