Fabrication of III-V semiconductor/Si heterojunctions without disturbance of inter-diffusion toward high frequency devices

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Formation of heterojunctions including Si opens a new path toward advanced Si devices. Although III-V semiconductors have a wide variation in terms of their bandgap, heterojunctions between III-V semiconductors and Si show a complicated doping profile due to an intermixing at the interface. Since N atoms are not electrically active in Si, the interface between a group-III nitride and Si is expected to show a simple configuration of the conduction type. Among group-III nitrides, InN with a bandgap of around 1.9 eV, which is close to the bandgap of Si, is a promising candidate for the Si heterojunction. In this study, InN was grown on Si(001) substrates at a substrate temperature of 500℃ by molecular beam epitaxy (MBE) using metal In and nitrogen radicals generated from nitrogen gas in rf plasma (13.56 MHz). The surface of the InN grown layer showed a mirror surface. Incorporations of In and N in the grown layer were confirmed by X-ray photoemission spectroscopy (XPS) measurement. The grown layer on Si with a thickness of 0.3 μm showed an oriented ring pattern in RHEED, and an X-ray diffraction peak ascribed to InN.Thereby, polycrystalline InN was grown in this study. The bandgap of the grown layer was measured to be 1.96 eV.The InN grown layer showed n^+-type without an intentional doping. The Hall mobility and the carrier concentration of InN were evaluated to be 28 cm^2/Vs and 3 × 10^<20> cm^<-3>, respectively. The band-offset of the InN/Si heterojunction was determined by XPS analysis on a very thin InN grown on n-type Si(001) substrate. The band-offset was measured to be 1.49 eV, indicating that the InN/Si heterojunction is a promising system to realize a barrier against holes in Si devices.