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 InGaAs surfaces. 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.

Crystalline and oxide phases revealed and formed on InSb(111)B

“…In particular, STS can provide information about prominent electronic states at or around the band gap area of the sample surface energy band and/or the pinning of Fermi-level 24,25 . Current imaging tunneling spectroscopy (CITS) is very useful in differentiating different electronic properties that possibly exist in two different lateral positions on the surface.…”

Bonding Geometries at the In2O and SiO/III-V Semiconductor Interface

“…In addition, the effects of postdeposition annealing on oxide bonding sites were investigated. The results are focused on InAs, but the results are readily applied to InGaAs systems due to similar surface structure and oxide bonding geometry (28).…”

The role of probe oxide in local surface conductivity measurements

“…A similar shift in the spectra observed by Shen and Clemens may be due to a similar effect as that observed here. 24,25 In their case, the oxide layer deposited on the InGaAs sample reduces the effect of the electric field and reduces the tip induced band bending which causes the CB edge to shift towards the Fermi level.…”

“…Studies carried out by Shen and Clemens show the effect on the STS spectra when a layer of indium oxide is deposited on InGaAs. 24,25 Both studies noted that the band edges shifted down in energy when a monolayer of In 2 O was deposited on n-type InGaAs and only the conduction band (CB) edge shifted towards the Fermi level when p-type InGaAs was used. Shen suggests that this behavior is due to surface band bending caused by surface dipoles or surface states.…”