Sub-10-nm Extremely Thin Body InGaAs-on-Insulator MOSFETs on Si Wafers With Ultrathin Al2O3 Buried Oxide Layers

We have demonstrated sub-10-nm extremely thin body (ETB) InGaAs-on-insulator (InGaAs-OI) nMOSFETs on Si wafers with Al2O3 ultrathin buried oxide (UTBOX) layers fabricated by direct wafer bonding process. We have fabricated the ETB InGaAs-OI nMOSFETs with channel thicknesses of 9 and 3.5 nm. The 9-nm-thick ETB InGaAs-OI nMOSFETs with a doping concentration (N-D) of 10(19) cm(-3) exhibit a peak electron mobility of 912 cm(2)/V . s and a mobility enhancement factor of 1.7 times against the Si nMOSFET at a surface carrier density (N-s) of 3 x 10(12) cm(-2). In addition, it has been found that, owing to Al2O3 UTBOX layers, the double-gate operation improves the cutoff properties. As a result, the highest on-current to the lowest off-current (I-on/I-off) ratio of approximately 10(7) has been obtained in the 3.5-nm-thick ETB InGaAs-OI nMOSFETs. These results indicate that the high-mobility III-V nMOSFETs can be realized even in sub-10-nm-thick channels.