Scanning tunneling microscopy/spectroscopy study of atomic and electronic structures of In2O on InAs and In0.53Ga0.47As(001)-(4×2) surfaces

Abstract

Interfacial bonding geometry and electronic structures of In 2 O on InAs and In 0.53 Ga 0.47 As ( 001 ) - ( 4 × 2 ) have been investigated by scanning tunneling microscopy/scanning tunneling spectroscopy (STM/STS). STM images show that the In 2 O forms an ordered monolayer on both InAs and InGaAssurfaces. In 2 O deposition on the InAs ( 001 ) - ( 4 × 2 ) surface does not displace any surface atoms during both room temperature deposition and postdeposition annealing. Oxygen atoms from In 2 O molecules bond with trough In/Ga atoms on the surface to form a new layer of O–In/Ga bonds, which restore many of the strained trough In/Ga atoms into more bulklike tetrahedral sp 3 bonding environments. STS reveals that for both p -type and n -type clean In 0.53 Ga 0.47 As ( 001 ) - ( 4 × 2 ) surfaces, the Fermi level resides near the valence band maximum (VBM); however, after In 2 O deposition and postdeposition annealings, the Fermi level position is close to the VBM for p -type samples and close to the conduction band minimum for n -type samples. This result indicates that In 2 O bonding eliminates surface states within the bandgap and forms an unpinned interface when bonding with In 0.53 Ga 0.47 As / InP ( 001 ) - ( 4 × 2 ) . Density function theory is used to confirm the experimental finding.