Evidence of real-space hot-electron transfer in high mobility, strained-Si multilayer MOSFETs

New phenomena are reported in N-MOSFETs with high-mobility, strained-Si electron channels. A parasitic bipolar breakdown is observed at anomalously low drain voltages at reduced temperatures (<100 K) in devices with strained-Si channels buried beneath a relaxed-Si/sub 1-x/Ge/sub x/ capping layer. This breakdown is consistent with a mechanism involving real-space hot-electron transfer and hole confinement in the heterostructure, and is shown to be quenched by the addition of a surface strained-Si layer. This additional Si layer also offers the practical advantage of extending device performance enhancements to higher gate voltages at room temperature.<>