The use of STEM imaging to analyze thickness variations due to electromigration-induced mass transport in thin polycrystalline nanobridges

Rudneva, Maria; Kozlova, Tatiana; Zandbergen, H.W.

doi:10.1016/j.ultramic.2013.05.022

Cited by 6 publications

(5 citation statements)

References 13 publications

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“…The bridge shown has a length of 1000 nm and a width of 500 nm. The STEM images were obtained with a medium camera length (117 mm) in order to record images of a good quality with a minimum of diffraction contrast, and thus to allow a contrast change to be attributed to a change in thickness [12]. The frame rate of the STEM footage was selected at 3 fps to achieve an acceptable image quality for the selected camera length.…”

Section: Resultsmentioning

confidence: 99%

In situTEM and STEM studies of reversible electromigration in thin palladium–platinum bridges

Kozlova

Rudneva²,

Zandbergen³

2013

Nanotechnology

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We investigated the reversible electromigration in Pd-Pt nanobridges by means of in situ electron microscopy. Real-time nanometer-scale imaging with scanning transmission electron microscopy was used to determine the material transport. For high current densities (3-5 × 10(7) A cm(-2)), material transport occurs from the cathode towards the anode side, indicating a negative effective charge. The electromigration is dominated by atom diffusion at grain boundaries on the free surface. The reversal of material transport upon a change of the electric field direction could be the basis of a memristor.

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Section: Resultsmentioning

confidence: 99%

In situTEM and STEM studies of reversible electromigration in thin palladium–platinum bridges

Kozlova

Rudneva²,

Zandbergen³

2013

Nanotechnology

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“…Using a high-angle annular dark field detector the contrast enhancement was achieved due to suppression of diffraction contrast while massthickness contrast leads to sufficient difference between high intensity NPs separated by almost no-intensity gaps. [32] The size distribution analysis was done by using the free ImageJ software. [33] SCO NPs were deposited using a stamping technique as previously published.…”

Section: Methodsmentioning

confidence: 99%

Spin Switching in Electronic Devices Based on 2D Assemblies of Spin‐Crossover Nanoparticles

et al. 2015

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Spin-crossover (SCO) materials form an intriguing class of compounds in which various external physical or chemical stimuli can change their ground spin state between a low-spin (LS) and a high-spin (HS) near room-temperature. [1][2][3][4] It has been a long standing dream to use this phenomenon in solid-state electronic devices. [5] Only recently several research groups succeeded in electrically addressing SCO materials based on Fe (II) coordination compounds at the nanoscopic [6][7][8] and microscopic [8][9][10] levels. This electric control of the spin has even been achieved in individual SCO molecules. [11,12] 2 The most investigated SCO systems are based on six-coordinated octahedral iron (II) complexes. In such systems, the spin state changes from the LS configuration, S = 0, to the HS one, S = 2; this SCO is accompanied by a change in the magnetic moment, the structure and color of the compound. Although the origin of this HS-LS transition is purely molecular, the SCO manifests cooperatively at the solid state and is strongly influenced by short/long range elastic interactions between neighboring SCO molecules. Such a cooperativity can result in a thermal hysteresis cycle, a property that can be used for memory applications in electronic devices. [5,13] In recent years the size of the SCO solid has been reduced to the nanoscale, while preserving the memory effect near room temperature. In particular, nanoparticles (NPs) of ~10 nm [14,15] have been obtained, based on the polymeric one-dimensional (1D) compound ([Fe(Htrz) 2 (trz)](BF 4 )), (Htrz = 1,2,4-triazole), [16,17] which is one of the most promising SCO systems for designing electronic devices working at room temperature. [14] SCO NPs of other materials forming 3D networks have also been studied in this context, but in most cases they undergo a fast decrease of the hysteresis width upon size reduction, which has been accompanied by a higher residual high spin fraction and a downshift of the transition temperatures. [19] Recently, the memory effect of the [Fe(Htrz) 2 (trz)](BF 4 ) NP(s) has electrically been demonstrated, [6,8,9] showing their potential as switching elements of nanoscale devices.Nevertheless, opposite behaviour in the conductivity change during the SCO transition has been reported, which remains unclear mainly due the scare experimental studies of the effects of an electric field on the charge transport properties. [20,21] In particular, measurements on single NP devices (NP mean size of 10 nm) show an increase in the electric conductivity when the SCO occurs, [6] whereas the reverse situation is observed for an assembly of NPs (mean size 15 nm) [8] and for larger particles [8][9][10] (from 100 to 300 nm in diameter and from 250 to a couple of microns in length). Although it is tempting to attribute this difference to 3 separate transport mechanisms operating in these devices, i.e, single-step tunnelling vs. multistep hopping, differences in the chemical and structural NP features as well as in the experimental conditions may not...

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“…3(a)-(e) shows snapshots of the real-time STEM movie recorded during bias-ramping at T s ¼ 420 K. To identify thickness changes due to Pt displacement, high-angle STEM imaging was used, which allowed the visualisation of material transfer, i.e. the thicker the area, the brighter it appears in the STEM image [12]. Six voltage loops with the maximum voltages in the range of 500-850 mV were applied in a row.…”

Section: Resultsmentioning

confidence: 99%

“…Such studies become more important because of the trend to downscale metallic contact lines to nanometer sizes in devices. To our knowledge, the influence of substrate temperature on bridge morphology during electromigration has not yet been reported, only results concerning room temperature (RT) and liquid nitrogen temperature (around 100 K) [2,11,12]. We report here on in situ TEM results of electromigration in Pt nanobridges at substrate temperatures ranging from 100 K to 660 K.…”

Section: Introductionmentioning

confidence: 94%

In situ visualisation of electromigration in Pt nanobridges at elevated temperatures

Kozlova

Zandbergen

2015

Ultramicroscopy

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The use of STEM imaging to analyze thickness variations due to electromigration-induced mass transport in thin polycrystalline nanobridges

Abstract: Highlights We analyzed the electromigration-induced thickness variations of thin polycrystalline films. Small camera length is required to minimize the effect of diffraction contact in STEM imaging

Cited by 6 publications

References 13 publications

In situTEM and STEM studies of reversible electromigration in thin palladium–platinum bridges

In situTEM and STEM studies of reversible electromigration in thin palladium–platinum bridges

Spin Switching in Electronic Devices Based on 2D Assemblies of Spin‐Crossover Nanoparticles

In situ visualisation of electromigration in Pt nanobridges at elevated temperatures

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