Analysis of InAs(001) surfaces by reflectance anisotropy spectroscopy

Abstract

Reflectance anisotropy spectroscopy (RAS) was applied to study the reconstructed surfaces of InAs(001) at room temperature. Arsenic-capped InAs samples, grown by molecular beam epitaxy, were annealed in ultrahigh vacuum. Low energy electron diffraction shows that, following As decapping, a 2 x 4 phase (As-rich) is obtained after annealing the sample at 340 degreesC (10 mins), while a subsequent annealing at 450 degreesC (15 mins) yields a 4 x 2 phase (In-rich). Using Kramers-Kronig relations, the anisotropy of the imaginary part of the surface dielectric function (Delta epsilon (s)") between [(1) over bar 10] and [110] directions of the substrate has been obtained from RAS data. We present both the RAS and Delta epsilon (s)" spectra characteristic of (2x4) and (4x2) reconstructed InAs(001) surfaces, and interpret the appearing features in terms of surface-state transitions and bulk transitions (modified by the surface). The experimental data are compared with the case of GaAs(001). Below 3 eV, the presence of As and In dimers at the surface gives rise to optical anisotropies centered at 2.4 and 1.7 eV, respectively, with opposite polarizations depending on the dimer-bond direction. At higher energies, a structure related to E-o' bulk critical point (at 4.4 eV) is visible

Growth of an InGaAs/GaAsSb tunnel junction for an InP-based low band gap tandem solar cell

“…Our RD spectra of the ð4 Â 2Þ=cð8 Â 2Þ reconstructed surface (Fig. 3c) looks similar to the InAs and GaAs ð4 Â 2Þ surfaces [7,8]. Two features at the E 1 and E 1 þ D 1 interband transition energies were already observed, even though were rather weak in comparison to our ð4 Â 3Þ and ð2 Â 4Þ RD spectra.…”

“…Therein, the two peaks correlating with the E 1 and E 1 þ D 1 interband transition energies have been observed again. Another maximum at 4.4 eV, as found for InAs and GaAs (at T ¼ 340 and 610 C) [7,8], can be observed in our RT RD spectrum. The minimum at 1.7 eV is broader and shifted to lower energies, compared with the ð4 Â 3Þ-reconstruction (compare Fig.…”

“…3a is shown for the first time. It shows a minimum at 1.9 eV, which is associated with In-and/or Ga-dimers [7,8]. Furthermore, there are two small peaks at 2.56 and 2.89 eV, which correlate with the interband transition energies E 1 ¼ 2:55 eV and E 1 þ D 1 ¼ 2:88 eV for In 0:53 Ga 0:47 As [9].…”

Optical properties of the GaAs(001)‐c(4 × 4) surface: direct analysis of the surface dielectric function

“…Recent interest has emerged in a layer-by-layer decomposition of the RAS signal within various ab initio frameworks: tight-binding [10], plane waves [11] and LMTO [12]. Further difficulty arises when the RAS signal contains uninteresting peaks arising from the real part of the surface dielectric function, as has been shown for InAs(001) [13]. In the present work we argue that the most physically accessible information is obtained from a real-space resolution of the surface dielectric function, which can be calculated directly.…”

Capping of InAs/GaAs Quantum Dots for GaAs Based Lasers

“…The signal intensity increases with increasing V/III ratio for InAs epitaxial surface, while it decreases for GaAs one. The reason of this behaviour is the change of dominant surface reconstruction for InAs from (4×2) to (2×4) with increasing V/III ratio, the relevant reflectance anisotropy spectra were reported in (Goletti et al, 2001;Knorr et al, 1997). (Kita, 2000).…”