PAMBE growth and in‐situ characterisation of clean (2 × 2) and (√3 × √3) R30° reconstructed InN(0001) thin films

Abstract

The surface properties of thin InN(0001) films grown by plasma assisted molecular beam epitaxy (PAMBE) were characterised. Two stable surface reconstructions (a (2 × 2) and a (√3 × √3) R30°) are identified which develop depending on the used preparation conditions. The structural, compositional and electronic surface properties were analysed in‐situ using reflection high energy electron diffraction (RHEED) and photoelectron spectroscopy (PES). From the absence of surface contaminants as well as excess indium it can be concluded that these superstructures are formed by single adatom layers. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Surface states and electronic structure of polar and nonpolar InN – An in situ photoelectron spectroscopy study

“…Therefore, we assign them to the occupied surface states which are related to the 2 Â 2 reconstruction. 4,22 According to the DFT results, the surface states determine the position of the surface Fermi level 0.7 eV above the CBM, which is in line with the band diagram shown in Fig. 2, and hence induce electron accumulation and downward bending at the InN(0001)-2 Â 2 surface.…”

“…21 All these mechanisms seem to be connected with the presence of characteristic occupied and unoccupied surface states that determine the surface Fermi level position and thereby the surface electron accumulation. [5][6][7] Surface states were already experimentally observed for In-polar and Npolar InN films, 4,13,22 while no measurements for nonpolar InN exist.…”

“…After growth, they exhibit a 2 Â 2 surface reconstruction. 4 As substrate for N-polar InN growth, n-doped Cpolar 6H-SiC(000-1) from SiCrystal was used. Prior to the InN MBE, a GaN buffer layer of $150 nm thickness was deposited.…”

“…More details about the experimental setup are published elsewhere. 4,23 The XPS survey spectra of the polar and nonpolar InN samples exhibit no signals originating from surface contaminations (detection limit $0.1 at. %).…”

Electron‐phonon‐plasmon interaction in MBE‐grown indium nitride – A high resolution electron energy loss spectroscopy (HREELS) study

“…Typically a (1×1) diffraction pattern is observed, in particular after the transfer of the samples under high vacuum conditions (p < 1×10 -5 mbar, transfer period ~ 40 min) to perform HREELS and low energy elec- tron diffraction (LEED) measurements. This transport results in a slight increase of surface contaminations by trace amounts of CH x (x = 1,2 or 3) and OH compared to in-situ studies [5]. However, the impurity level is much lower compared to samples exposed to ambient conditions even for a limited time [6].…”