Channel design and mobility enhancement in strained germanium buried channel MOSFETs

In this work, the channel design space for scaled strained Ge (s-Ge) buried channel (BC) MOSFETs is examined by simulations and experiments. The identified Ge channel layer structure is scalable to sub-30nm devices. Furthermore, strained Ge buried-channel MOSFETs with an ultra thin (l.5nm) Si cap are demonstrated with a 6X hole mobility enhancement over the Si universal hole mobility. Compared with surface channel Ge MOSFETs, buried strained Ge channel structures can be integrated with fewer processing challenges to achieve a significantly enhanced hole mobility and an improved electron mobility.