Formation of polar InN with surface Fermi level near the valence band maximum by means of ammonia nitridation

• Development of InN films for devices is hindered due to metallic In clusters, formed readily during growth, and unintentional n-type conductivity of the nominally undoped films, including surface electron-accumulation layers via the Fermi level pinning into the conduction band. Plasma nitridation eliminates even large In clusters from the surface by changing them to two-dimensional InN [Yamaguchi and Nanishi, Appl. Phys. Expr. 2, 051001 (2009)]. Here we utilized a similar approach, that is, nitridation of In-covered surfaces with ammonia (NH3) to grow thin, up to 25 nm thick polar InN films on Si(111) and GaN(0001) substrates. By means of scanning tunneling microscopy and spectroscopy, as well as photoelectron spectroscopy, we show that this simple NH3 nitridation provides the hitherto not reported formation of polar InN(000-1) films with the surface Fermi level close to the valence band maximum, as recent calculations [Belabbes et al., Phys. Rev. B 84, 205304 (2011)] predict. DOI: 10.1103/PhysRevB.86.245304

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NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

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