High mobility strained Si0.5Ge0.5/SSOI short channel field effect transistors with TiN/GdScO3 gate stack
Short channel p-type metal-oxide-semiconductor field effect transistors (MOSFETs) with GdScO3 gate dielectric were fabricated on a quantum well strained Si/strained Si0.5Ge0.5/strained Si heterostructure on insulator. Amorphous GdScO3 layers with a dielectric constant of 24 show small hysteresis and low density of interface states. All devices show good performance with a threshold voltage of 0.585V, commonly used for the present technology nodes, and high Ion/Ioff current ratios. We confirm experimentally the theoretical predictions that the drive current and the transconductance of the biaxially strained (100) devices are weakly dependent on the channel orientation. The transistors hole mobility, extracted using split CV method on long channel devices, indicates an enhancement of 90% (compared to SiO2/SOI transistors) at low effective field, with a peak value of 265cm2/Vs. The enhancement is however, only 40% at high electrical fields. We demonstrate that the combination of GdScO3 dielectric and strained SiGe layer is a promising solution for gate-first high mobility short channel p-MOSFETs.
strained si sige high-k dielectrics silicon on insulator advanced mosfet