Abstract
Oxidation treatment creating a well-ordered crystalline structure has been shown to provide a major improvement for III–V semiconductor/oxide interfaces in electronics. We present this treatment’s effects on InSb(111)B surface and its electronic properties with scanning tunneling microscopy and spectroscopy. Possibility to oxidize (111)B surface with parameters similar to the ones used for (100) surface is found, indicating a generality of the crystalline oxidation among different crystal planes, crucial for utilization in nanotechnology. The outcome is strongly dependent on surface conditions and remarkably, the (111) plane can oxidize without changes in surface lattice symmetry, or alternatively, resulting in a complex, semicommensurate quasicrystal-like structure. The findings are of major significance for passivation via oxide termination for nano-structured III–V/oxide devices containing several crystal plane surfaces. As a proof-of-principle, we present a procedure where InSb(111)B surface is cleaned by simple HCl-etching, transferred via air, and post-annealed and oxidized in ultrahigh vacuum.
Highlights
InSb crystals have been increasingly investigated in order to develop low band gap (~0.2 eV) and high electron mobility (~80 000 cm[2] V−1 s−1) demanding electronics devices, and various prospective future applications
To confirm optimally clean starting conditions and to be able to utilize same sample for multiple experiments, mainly sputtering and annealing treatments were used to clean the samples in further experiments, but it is noteworthy that the effects which are discussed here were observed for samples cleaned with HCl
We suggest that the most stable oxide phase is achieved by inserting O into In-bonds which results in (3 × 3)–O when the hexamers are initially stabilized in parallel orientation, which seems to be the case in roughened areas or such that are rich in step-edges
Summary
InSb crystals have been increasingly investigated in order to develop low band gap (~0.2 eV) and high electron mobility (~80 000 cm[2] V−1 s−1) demanding electronics devices, and various prospective future applications. It is very difficult in practice to avoid the formation of natively oxidized surface on InSb crystals during the manufacturing of the devices Because such native oxide films usually lack long range order and are rich in defects, including high densities of electronic defects levels at the interface, these InSb surfaces oxidized in uncontrolled manner are a performance limiting part of many devices. Current imaging tunneling spectroscopy (CITS) is very useful in differentiating different electronic properties that possibly exist in two different lateral positions on the surface These tools are utilized here to observe effects on InSb(111)B induced by oxidation treatments.
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