Plasma-assisted MBE growth of InN film and InAlN/InN heterostructure

InN has not been studied so much among III-nitride compound semiconductors, even though it is an attractive material from the viewpoint of practical device application. Theoretical studies have predicted that its saturation and overshoot electron velocities in InN film would be the highest among nitride compounds and that InN-based transistors would be extremely fast and have a cutoff frequency of over 1 THz. However, InN epitaxial film and InN-based heterostructures with quality sufficient for practical device application have not been obtained due to difficulties with InN epitaxial growth, such as a low dissociation temperature and the lack of a suitable lattice-matched substrate. We have reported that a buffer layer formed with a low-temperature-grown GaN (LT-GaN) intermediate layer and a LT-InN layer on a sapphire substrate improves electrical and structural properties of InN epitaxial film. The highest Hall mobility and lowest carrier density of our plasma-assisted MBE-grown InN film at room temperature were 1420 cm/sup 2//V/spl middot/s and 1.4/spl times/10/sup 18/ cm/sup -3/, respectively. In this summary, we report on plasma-assisted MBE growth of InN thin film and of an InAlN/InN heterostructure on a sapphire substrate.