Termination, surface structure and morphology of the molecular beam epitaxially grown HgTe(001) surface

Abstract

The surface structure of molecular beam epitaxially grown HgTe(001) has been studied under in situ ultrahigh vacuum conditions. The as-grown samples were investigated by means of x-ray photoelectron spectroscopy (XPS), spot profile analysis of low-energy electron diffraction, reflection of high-energy electron diffraction and scanning tunneling microscopy (STM). They exhibited a c(2×2) surface reconstruction with an additional weak (2×1) component in both diffraction experiments. The surface was shown by XPS to be terminated with Hg atoms. In addition, by means of STM experiments, we have been able to resolve the atomic structure of the reconstructed surface and to detect domain boundaries along the [11̄0] direction whose local symmetry is twofold and, therefore, the probable cause of the weak (2×1) reconstruction.

Molecular Beam Epitaxy of HgCdTe Materials and Detectors

“…This is in contrast to the step flow growth mechanism for Hg 1Àx Cd x Te, in which ML high steps grow at the same rate. The width of these steps is dependent on orientation as can be seen by the in situ high-resolution scanning tunnel microscope (STM) image (Oehling et al, 1998) of HgTe(100) (Figure 4) and the highresolution atomic force microscopic (AFM) image (Schmidt et al, 2002) of Hg 0.8 Cd 0.2 Te (211)B ( Figure 5). These widths are approximately 50 and 18 nm for (100) and (211) orientations, respectively.…”

“…In the case of the (100) orientation, the steps are arranged in mounds of terraces whose long axis is oriented in the [ " 110] direction as shown in Figures 4 and 6 (Oehling et al, 1998). The terraces are 1 ML high, that is, 0.32 AE 0.03 nm and, on average, 50 nm wide.…”

Band Discontinuity and Band Gap of MBE Grown HgTe/CdTe(001) Heterointerfaces Studied by k-Resolved Photoemission and Inverse Photoemission

“…The shallow core levels, Hg 5d and Cd 4d, of the two bulk samples and of the 3 # e HgTe/CdTe heterojunction shown in for the determination of the valence band offset. The weak shoulders at the high-energy side of the Hg 5d levels are due to surface core level shifted components, demonstrating the surface termination by Hg [18]. The energy positions of the Cd 4d levels of the CdTe bulk sample shown here, are corrected by the energy separation of the valence band maxima of CdTe and HgTe, DE VBM (CdTe±HgTe) 0.78 eV, i.e., relative to the VBM of HgTe.…”

Ehrlich-Schwoebel barrier controlled slope selection in epitaxial growth

“…Even though the Zeno-effect has been observed recently on Pt(111) [6], quite typically a coarsening process with appearance of slope selection emerges which has been reported for such diverse systems as Fe(001) [7,8], Cu(001) [9,10], GaAs(001) [11,12], and HgTe(001) [13]. In addition, slope selection seems to be the generic case of solid-on-solid computer simulations [14,12,15].…”