Ultrathin compound semiconductor on insulator layers for high-performance nanoscale transistors

Abstract

Over the past several years, the inherent scaling limitations of silicon (Si) electron devices have fuelled the exploration of alternative semiconductors, with high carrier mobility, to further enhance device performance^{1,2,3,4,5,6,7,8}. In particular, compound semiconductors heterogeneously integrated on Si substrates have been actively studied^7,9,10: such devices combine the high mobility of III–V semiconductors and the well established, low-cost processing of Si technology. This integration, however, presents significant challenges. Conventionally, heteroepitaxial growth of complex multilayers on Si has been explored^9,11,12,13—but besides complexity, high defect densities and junction leakage currents present limitations in this approach. Motivated by this challenge, here we use an epitaxial transfer method for the integration of ultrathin layers of single-crystal InAs on Si/SiO₂ substrates. As a parallel with silicon-on-insulator (SOI) technology¹⁴, we use ‘XOI’ to represent our compound semiconductor-on-insulator platform. Through experiments and simulation, the electrical properties of InAs XOI transistors are explored, elucidating the critical role of quantum confinement in the transport properties of ultrathin XOI layers. Importantly, a high-quality InAs/dielectric interface is obtained by the use of a novel thermally grown interfacial InAsO _x layer (~1 nm thick). The fabricated field-effect transistors exhibit a peak transconductance of ~1.6 mS µm⁻¹ at a drain–source voltage of 0.5 V, with an on/off current ratio of greater than 10,000.