SURFACE PASSIVATION EFFECT IN SGOI NANOWIRE BIOSENSOR WITH HIGH GE FRACTION

Abstract

The increase of surface to volume ratio results in the enhancement of the sensitivity of the nanowires. Our previous studies have shown that the higher Ge fraction of Si1-xGex nano-wire improves the sensitivity of the nanowire biosensor as a result of carrier mobility enhancement in strain-Si. Increasing the fraction of Ge in SiGe-on-Insulator (SGOI) using Ge condensation by oxidation has obtained a significant enhancement in hole mobility, further improving the sensitivity of SGOI nanowire. However, the sensitivity of SGOI nanowire was degraded for exceeding a Ge fraction of 20% (i.e., high Ge fraction), resulting from the unstable surface state. In this work, a top surface passivation SiO2 layer was deposited on Si0.8Ge0.2 nanowire and the sensitivity was about 1.3 times greater than nanowire sample without the top passivation layer.