Hot electron spectroscopy and microscopy

Smoliner, J.; Rakoczy, D.; Kast, M.

doi:10.1088/0034-4885/67/10/r04

Cited by 39 publications

(28 citation statements)

References 173 publications

(230 reference statements)

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“…13,14 After scattering in the metal stack, some electrons can reach the semiconductor/ metal interface with the proper energy and momentum required to overcome the Schottky barrier at this interface and be collected into the semiconductor, 11,13,15 forming the collector current I C . I C depends on the relative alignment of the magnetization of the sample and the ferromagnetic layer in the tip, in analogy with the prototypical polarizer-analyzer optical experiment.…”

Section: Fig 1 Schematic Of Tip-sample Configuration Used For Sf-stmentioning

confidence: 99%

Multiterminal semiconductor/ferromagnet probes for spin-filter scanning tunneling microscopy

Marun

Jansen

2009

Journal of Applied Physics

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We describe the fabrication of multiterminal semiconductor/ferromagnet probes for a new technique to study magnetic nanostructures: spin-filter scanning tunneling microscopy. We describe the principle of the technique, which is based on spin-polarized tunneling and subsequent analysis of the spin polarization using spin-dependent transmission in the probe tip. We report the fabrication of the probes having a submicron semiconductor/ferromagnet heterostructure at the end of the tip.The continuous reduction in critical feature sizes in both magnetic data storage and semiconductor technologies requires characterization techniques with ever higher spatial resolution. The emerging field of spintronics 1 also requires appropriate techniques to study spin-related phenomena in magnetic nanostructures. 2 Scanning probe techniques 3 such as magnetic force microscopy ͑MFM͒ and spin-polarized scanning tunneling microscopy ͑SP-STM͒ are frequently employed. MFM is versatile because it does not require ultraclean nor conducting samples. However, as it relies on magnetic stray fields, the data interpretation are not always straightforward, while the typical best resolution is limited at around 20 nm, 4,5 which is close to the critical feature size in magnetic nanostructures.SP-STM is a powerful technique in terms of the wealth of electronic information it provides, including the position of exchange-split features in the local density of states ͑LDOS͒, 6 and has proven capable of the ultimate resolution by imaging magnets at the atomic scale. 7,8 SP-STM is usually performed in the differential conductivity mode 6 where its need for exchange-split states to produce strong features in the LDOS, low temperatures, and its spectroscopic nature limits its applicability and makes the extraction of quantitative magnetic information more difficult. To obtain the sample tunneling spin polarization ͑TSP͒ with SP-STM, one must know the corresponding TSP of the last atoms of the tip ͑magnitude and direction͒, which may not be a trivial matter. Thus, it would be highly desirable to have a technique capable of measuring directly and quantitatively the sample spin polarization at Fermi level and with atomic resolution. This is of importance for assessing spin transport in new materials and devices. 9 Here we propose a novel technique, namely, spin-filter scanning tunneling microscopy ͑SF-STM͒. As in SP-STM, this new technique relies on spin-polarized tunneling between tip and sample to extract magnetic information from surfaces. The difference is that in SF-STM, the spin analysis occurs within the tip in a semiconductor/ferromagnet heterostructure-after tunneling. The novel tip design consists of a top metallic surface where tunneling takes place, followed by a semiconductor/ferromagnet heterostructure in which transmission is spin dependent ͑see Fig. 1͒. There are two separate contacts to the tip, one to the metallic surface, the other to the semiconductor. Magnetic contrast is provided by the dc measurement of the current collected in the sem...

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Section: Fig 1 Schematic Of Tip-sample Configuration Used For Sf-stmentioning

confidence: 99%

Multiterminal semiconductor/ferromagnet probes for spin-filter scanning tunneling microscopy

Marun

Jansen

2009

Journal of Applied Physics

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“…Its optical counterpart, Ballistic Electron Emission Luminescence (BEEL), has enabled the study of luminescence from buried structures [5,6], but thus far the spectroscopic study of luminescence from a single buried structure such as a quantum dot has remained elusive. The primary obstacle to such an experiment is the low collector current attainable in conventional BEES/BEEL techniques, which typically utilize a thin metal layer for the base electrode [7,8]. Electrons tunnel into the base metal, and, except in select systems such as epitaxial Bi on Si [9], the vast majority (>99.9%) are unable to traverse it and enter the semiconductor before they scatter and thermalize to the chemical potential of the base layer.…”

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confidence: 99%

Direct injection tunnel spectroscopy of a p-n junction

Likovich

Russell

Narayanamurti

et al. 2009

Applied Physics Letters

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We demonstrate spectroscopic measurements on an InGaAs p-n junction using direct tunnel injection of electrons. In contrast to the metal-base transistor design of conventional ballistic electron emission spectroscopy (BEES), the base layer of our device is comprised of a thin, heavily doped p-type region. By tunneling directly into the semiconductor, we observe a significant increase in collector current compared to conventional BEES measurements. This could enable the study of systems and processes that have thus far been difficult to probe with the low-electron collection efficiency of conventional BEES, such as luminescence from single-buried quantum dots.

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“…Here we will give a brief description of the technique in order to understand the major differences relative to regular STM and how the magnetic counterpart of BEEM can be used to image magnetic nanostructures. For a thorough description of the transport processes involved in BEEM and related techniques we refer the reader to the extensive early review by Prietsch [85] and to more recent ones [86,87,88].…”

Section: Ballistic Electron Magnetic Microscopymentioning

confidence: 99%

“…It uses the framework of planar tunneling (similar as Equation 2.3) with the tunneling probability (Equation 2.1) depending only on the energy component E x normal to the tunnel barrier. For the collector current two extra restrictions apply [87]. First, electrons must have enough energy to surmount the Schottky barrier so there is a minimum allowed energy E min…”

Section: Ballistic Electron Magnetic Microscopymentioning

confidence: 99%

“…Therefore we use the BK model to extract Schottky barrier heights and compare spectra in this thesis, with η = 2 (and η = 4 for operation in reverse mode [110]). More advanced models are considered in recent reviews [86,87]. Imaging of spin-valve structures with BEMM has proven to achieve magnetic resolution better than 50 nm when collecting hot electrons [111] and better than 30 nm when collecting hot holes [98].…”

Section: Ballistic Electron Magnetic Microscopymentioning

confidence: 99%

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Spin-filter scanniing tunneliing microscopy : a novel technique for the analysis of spin polarization on magnetic surfaces and spintronic devices

Vera‐Marun

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Hot electron spectroscopy and microscopy

Cited by 39 publications

References 173 publications

Multiterminal semiconductor/ferromagnet probes for spin-filter scanning tunneling microscopy

Multiterminal semiconductor/ferromagnet probes for spin-filter scanning tunneling microscopy

Direct injection tunnel spectroscopy of a p-n junction

Spin-filter scanniing tunneliing microscopy : a novel technique for the analysis of spin polarization on magnetic surfaces and spintronic devices

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