Laterally-scaled Si/SiGe n-MODFETs with in situ and ion-implanted p-well doping

In order to fulfill their potential for enhanced performance, MODFETs must be scaled, both laterally and vertically. However, lateral scaling is particularly challenging because well and/or halo doping can lead to dopant incorporation in the 2D channel which can significantly degrade the mobility. Recently, we have demonstrated a technique for growing Si/SiGe n-MODFET layer structures with buried p-well doping while retaining an undoped channel region. In this paper, we describe the operation of laterally-scaled Si/SiGe n-MODFETs with buried in situ and ion-implanted p-well doping. We show that the devices have improved subthreshold behavior, greatly improved self-gain and improved speed-power product compared with undoped controls.