Conduction studies on bismuth selenide thin films
TL;DR: In this paper, the capacitance and dielectric constant have been measured from 303 K to 383 K in the frequency range of 10 kHz to 10 MHz, the a.c. conductivity σ is calculated at different frequencies for various temperatures.
Abstract: Thin films of Bi 3 Si 3 have been prepared by vacuum deposition technique onto well cleaned glass and freshly cleaved KBr substrates. The film thicknesses are measured by Tolansky technique. The capacitance and dielectric constant have been measured from 303 K to 383 K in the frequency range of 10 kHz to 10 MHz, The a.c. conductivity σ is calculated at different frequencies for various temperatures. The relation σ ω 1 fits well and the value of n is found to be greater than 1.5 and above at high frequencies suggests that the conduction mechanism in Bi 2 Se 3 thin fil is hopping. The d.c. conduction studies revealed the non-ohmic type of conduction Log 1 versus Log V plot). From the Log 1 versus F 2 plot, the field lowering coefficient β is evaluated.
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TL;DR: An overview of MEMS failure mechanisms that are commonly encountered is provided, focusing on the reliability issues of micro-scale devices, but, for some issues, the field of their macroscopic counterparts is also briefly touched.
300 citations
Cites methods from "Conduction studies on bismuth selen..."
...With field strengths this high, conduction is not governed anymore by Ohm s law, but by non-linear conduction effects due to charge injection and conduction via traps, like Schottky- and Poole–Frenkel type conduction [80]....
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TL;DR: In this paper, different compositions of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) blends have been prepared using the casting method using differential scanning calorimetery (DSC), TGA and dielectric spectroscopy of all compositions.
Abstract: Films with different compositions of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) blends have been prepared using the casting method. Differential scanning calorimetery (DSC), thermogravimetric analysis (TGA) and dielectric spectroscopy of all compositions have been investigated. It was found that PVA and CMC are compatible in the studied range of composition. With increasing CMC content, the thermal stability of PVA increases. Based on DSC and TGA data, the activation energies of all the investigated samples were calculated. The absorption edge ( E a ) was also determined from Ultraviolet–visible (UV–vis) spectra. Dielectric permittivity, loss tangent and ac conductivity of all samples were studied as functions of temperature and frequency. The results show that the dielectric dispersion consists of both dipolar and interfacial polarization. The frequency dependence of the ac conductivity indicates that the correlated barrier hopping (CBH) is the most suitable mechanism for conduction. The polaron binding energy ( U M ) was determined. Results of the present system are compared with those of similar materials.
222 citations
TL;DR: In this paper, a two-step growth method was adopted for the van der Waals epitaxy of Bi2Se3 to proceed, and the in-plane growth rate anisotropy was exploited in order to achieve single crystalline Bi 2Se3 epifilms, in which threading defects and twins were effectively suppressed.
Abstract: The epitaxial growth of thin films of the topological insulator Bi2Se3 on nominally flat and vicinal Si(111) substrates was studied. In order to achieve a planar growth front and better quality epifilms, a two-step growth method was adopted for the van der Waals epitaxy of Bi2Se3 to proceed. By using vicinal Si(111) substrate surfaces, the in-plane growth rate anisotropy of Bi2Se3 was exploited in order to achieve single crystalline Bi2Se3 epifilms, in which threading defects and twins are effectively suppressed. The optimization of the growth parameters has resulted in the vicinal Bi2Se3 films showing a carrier mobility of ~2000 cm2 V−1 s−1 and a background doping of ~3×1018 cm−3 of the as-grown layers. Such samples not only show a relatively high magnetoresistance but also show a linear dependence on the magnetic field.
201 citations
TL;DR: The common failure mechanisms in MEMS, including mechanical fracture, fatigue, creep, stiction, wear, electrical short and open, contamination, their effects on devices' performance, inspection techniques, and approaches to mitigate those failures through structure optimization and material selection are reviewed.
Abstract: Microelectromechanical systems (MEMS) represents a technology that integrates miniaturized mechanical and electromechanical components (i.e., sensors and actuators) that are made using microfabrication techniques. MEMS devices have become an essential component in a wide range of applications, ranging from medical and military to consumer electronics. As MEMS technology is implemented in a growing range of areas, the reliability of MEMS devices is a concern. Understanding the failure mechanisms is a prerequisite for quantifying and improving the reliability of MEMS devices. This paper reviews the common failure mechanisms in MEMS, including mechanical fracture, fatigue, creep, stiction, wear, electrical short and open, contamination, their effects on devices' performance, inspection techniques, and approaches to mitigate those failures through structure optimization and material selection.
150 citations
Cites background from "Conduction studies on bismuth selen..."
...Conduction is no longer governed by Ohm’s law, but by nonlinear conduction, such as Schottky-type and Poole–Frenkel-type conduction, which is due to charged particle injection and via traps [91]....
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TL;DR: The metal-organic compounds, Bi[(EPR2)2N]3 (E = S, Se; R = Ph, iPr), have been synthesized and used as single-source precursors for the deposition of bismuth chalcogenide thin films via low-pressure and aerosol-assisted metalorganic chemical vapor deposition.
Abstract: The metal-organic compounds, Bi[(EPR2)2N]3 (E = S, Se; R = Ph, iPr), have been synthesized and used as single-source precursors for the deposition of bismuth chalcogenide thin films via low-pressure and aerosol-assisted metal-organic chemical vapor deposition. Crystalline thin films of rhombohedral Bi2Se3 (using Bi[(SePiPr2)2N]3), hexagonal BiSe (using Bi[(SePPh2)2N]3), and orthorhombic Bi2S3 (using Bi[(SPR2)2N]3) have been deposited on glass substrates. Films have been characterized by X-ray powder diffraction, scanning electron microscopy, and energy-dispersive analysis of X-rays.
113 citations
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TL;DR: In this article, the authors investigated the electrical conduction process in amorphous solids, using as a basis the ionization of local defects by an applied field, and showed that the Poole-Frenkel effect is a limiting case of a more general analysis that can be extended to cover the experimentally available range of field stress and temperature.
Abstract: The nature of the electrical conduction process in amorphous solids, using as a basis the ionization of local defects by an applied field, is investigated. It is shown that the Poole-Frenkel effect is a limiting case of a more general analysis that can be extended to cover the experimentally available range of field stress and temperature. At low temperature conduction is by tunnelling emission out of the defects into the quasi-conduction band of the host material whereas at high temperatures thermal emission becomes dominant. Between the two regions a thermal-field emission process has been identified with the characteristic of ln J ∝ T −⅓.
560 citations
TL;DR: In this paper, the authors investigated the ac conductivity of glasses due to atomic and electronic hopping between sites with random space and energy separations and found that glassy materials should quite generally exhibit a nearly linear conductivity-frequency relationship.
Abstract: We investigate the ac conductivity of glasses due to atomic and electronic hopping between sites with random space and energy separations. Several examples are considered including the structural model of glasses recently introduced by Anderson, Halperin, and Varma, and by Philips. We find that glassy materials should quite generally exhibit a nearly linear conductivity-frequency relationship. The details of any particular conductivity mechanism should be contained in the deviation from linearity.
364 citations
TL;DR: In this article, the loss tangent and permittivity of vacuum- baked dielectric films of anodized aluminium oxide and evaporated silicon oxide, in the frequency range 10 -2 -10 7 Hz and temperature range 77-600 °K, were reported.
231 citations
TL;DR: In this article, single crystals of n-type Bi2Se3 grown by the Bridgman technique are found to make excellent Hall effect magnetometers capable of repeated cycling to liquid helium temperatures.
Abstract: Single crystals of n‐type Bi2Se3 grown by the Bridgman technique are found to make excellent Hall effect magnetometers capable of repeated cycling to liquid helium temperatures. Plots of Hall resistivity, ρyx, versus magnetic field B to 11 tesla deviate from linearity by less than ±0.8% for all temperatures between 1.1 and 300 K. Furthermore, the slope of the ρyx versus B curve varies by less than 2% in the region 1.1 to 78 K.
23 citations