Electrical and Surface Properties of InAs/InSb Nanowires Cleaned by Atomic Hydrogen

Abstract

We present a study of InAs/InSb heterostructured nanowires by X-ray photoemission spectroscopy (XPS), scanning tunneling microscopy (STM), and in-vacuum electrical measurements. Starting with pristine nanowires covered only by the native oxide formed through exposure to ambient air, we investigate the effect of atomic hydrogen cleaning on the surface chemistry and electrical performance. We find that clean and unreconstructed nanowire surfaces can be obtained simultaneously for both InSb and InAs by heating to 380 ± 20 °C under an H2 pressure 2 × 10(-6) mbar. Through electrical measurement of individual nanowires, we observe an increase in conductivity of 2 orders of magnitude by atomic hydrogen cleaning, which we relate through theoretical simulation to the contact-nanowire junction and nanowire surface Fermi level pinning. Our study demonstrates the significant potential of atomic hydrogen cleaning regarding device fabrication when high quality contacts or complete control of the surface structure is required. As hydrogen cleaning has recently been shown to work for many different types of III-V nanowires, our findings should be applicable far beyond the present materials system.

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

“…For example, InSb is utilized nowadays in infrared detectors and is very potential for high-speed transistors operating at low voltages 1–6 and other ultra thin device applications 7,8 , and very recently, e.g., as building blocks of quantum computers 9 and THz transport waveguides 10 . The common challenge in developing these various InSb-based devices is how the surface or interface properties of InSb crystals can be modified in controlled manner.…”

“…Furthermore, 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. Indeed, controlled modifications of the oxidized surfaces have been intensively researched and developed 7,11–13 .…”

“…This is the same method we have used previously for preparing crystalline oxidized III–V(100) surfaces 14 , found to reduce the amount of defect states by over an order of magnitude beneath an atomic layer deposition (ALD) grown oxide film 15 and thus enabling efficient passivation. However, the following crucial questions have previously remained unresolved: (i) is the crystalline oxidation possible for other crystal planes; in more general for various crystal faces [not only (100) planes] exposed in nanotechnology 2,7–9,12,16,17 , and (ii) how to produce clean InSb surfaces in an industrially potential way, which is necessary in order to perform the crystalline pre-oxidation in practice. Here we provide solutions to these questions using InSb(111)B as a template for investigations.…”

Hot Electrons Regain Coherence in Semiconducting Nanowires

“…In spite of the growing interest in semiconducting nanowires [22][23][24][25][26][27], little is known on their electronic band structure and energy dispersion. In particular, very few STM spectroscopic studies have been conducted on semiconducting nanowires [28][29][30][31], although STM is potentially apt towards spectroscopic visualization on the nanoscale. The main technological challenge lies in the nanowires brittleness and high surface reactivity that hamper the ability to probe their surface.…”

Formation of GaAs/GaSb Core-Shell Heterostructured Nanowires Grown by Molecular-Beam Epitaxy

“…Furthermore, the transportation path and the charge carrier type of GaSb/InAsSb core-shell NWs can be tuned by changing the thickness of the NW shells and the applied bias voltage [28]. According to recent reports about InAs/InSb [29] and GaAs/GaSb [30], research has been mainly focused on axial heterostructures, while there are few reports about core-shell NWs.…”