Some aspects of raman scattering in Cd<sub>3</sub>As<sub>2</sub> single crystals

Weszka, J.; Renucci, M. A.; Zwick, A.

doi:10.1002/pssb.2221330106

Cited by 19 publications

(15 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A consistent blueshift of ≈15 cm −1 that is evident for both modes points to a residual compressive strain induced as a result of platelet cooling, Figure 3 , the inset. The lowest, high intensity mode at 210 cm −1 (195 cm −1 in target) coincides with 196 cm −1 phonon-allowed mode reported by Jandl et al [ 19 ] and Weszka et al, [ 20 ] whereas the largest intensity mode at 265 cm −1 (249 cm −1 in target) was also predicted and reported to exist in α-Cd 3 As 2 by Weszka. [ 20 ] The bulk crystal structure of Cd 3 As 2 ( a = 1.267 nm and c = 2.548 nm) comprises a face-centered cubic lattice for As with six Cd atoms occupying the eight corners of an inner cube (two diagonally opposite corners of a cubic face remain empty).…”

supporting

confidence: 85%

Large Thermopower, Crystalline Cd₃As₂ by Low‐Temperature Vapor Deposition for Room Temperature Heat Waste Recovery

Hosseini

Yavarishad

Alward

et al. 2015

Adv Elect Materials

View full text Add to dashboard Cite

carrier back-scattering remains suppressed and the electrical transport is dominated by high-energy carriers that favorably affect the thermopower of Cd 3 As 2 . [ 9 ] Since the power factor is to increase with the carrier mobility, µ , and weighted density-ofstates effective mass, i.e., S 2 σ ≈ µ D *1.5 m , and the lattice thermal conductivity is predicted to be very low, Cd 3 As 2 shows a strong potential for demonstrating high, device-favorable S , and in turn ZT , Table 1 . [ 10 ] Binary cadmium arsenide that solidifi es as Cd 3 As 2 is known to undergo multiple polymorphic solid-solid transitions β α α α → ′′ → ′ → at T of 578, 475, and 225 °C, respectively; the latter of which limits the growth temperature to 225 °C. Given the melting point of this compound of 721 °C, melt-based crystal growth techniques have to be ruled out from consideration. Pulsed-laser evaporation was offered as an alternative route, [ 17 ] but the resultant samples show highly reduced, i.e., polycrystalline and amorphous quality.In this work, a low-T chemical-vapor deposition route is used instead to grow platelets up to cm size in Cd 3 As 2 in a horizontally oriented hot-wall atmospheric pressure chemical vapor deposition (CVD) reactor. To lower the residual pressure of oxygen and water vapors, the reactor was initially fl ushed several times by bringing the base pressure down to ≈1 m Torr and refi lling it with 99% pure argon gas. The temperature of the furnace was gradually ramped up from ≈25 to 700 °C (measured at the middle point of the quartz tube) within an hour. Pure, polycrystalline Cd 3 As 2 chunks were used as a precursor, while quartz and alumina wafers served as growth substrates. To facilitate vapor transport of Cd and As, a steady argon fl ow was maintained within the reactor with the rate of ≈0.2 SCCM. The growth duration was set not to exceed 3 h. Upon completion, the heater was shut down and the reactor was left to cool down naturally at the average rate of ≈5 °C min −1 in the presence of argon fl ow. Except for the tube end points, the temperature gradient (as probed with the help of IR temperature sensor) along the tube main axis, T ∇ was on average a few degrees per cm, Figure 1 , top.After the growth, the substrate as well as the reactor sidewalls was subject to visual and optical microscope inspections, Thermoelectric generators (TEGs) directly convert thermal into electrical energy and are the prime candidates for application in low-grade thermal energy/heat waste recovery. These solidstated devices demonstrate several critical advantages over other power generators as they are silent, very reliable, and compact/lightweight, which make them attractive for several niche deployments including transportation, space satellites, electronics cooling, and thermovoltaic cells. [1][2][3] Yet, TEGs with typical effi ciency of only ≈5%-8% demonstrate poor effi ciencyto-cost ratio, and the problem stems mainly from the poor conversion characteristics of the thermoelectric (TE) materials themselves.The TE performance is rou...

show abstract

supporting

confidence: 85%

Large Thermopower, Crystalline Cd₃As₂ by Low‐Temperature Vapor Deposition for Room Temperature Heat Waste Recovery

Hosseini

Yavarishad

Alward

et al. 2015

Adv Elect Materials

View full text Add to dashboard Cite

show abstract

“…We find an additional peak at 178 cm À1 and two more modes at around 300 cm À1 , which coincide with a mode at 300 cm À1 reported by Weszka et al 13 The authors did not comment on the satellite peak at 309 cm À1 , which has half of the intensity of the main peak. 13 III-V compound nanowires are usually grown in a selfcatalyzed process with or without a group-III element acting catalytically and being located at the tip of the nanowire. It was shown that the presence of the catalytic tip depends on the group-V flux during cool-down.…”

supporting

confidence: 83%

Structural properties and growth mechanism of Cd3As2 nanowires

Schönherr

Hesjedal

2015

Applied Physics Letters

View full text Add to dashboard Cite

Cadmium arsenide (Cd3As2) is a material well-known for its very high room-temperature carrier mobility. Recently, it has also been shown to be a three-dimensional Dirac semimetal—the three-dimensional analogue of graphene. Here, we present a detailed structural study of the self-catalyzed growth of Cd3As2 nanowires. The crystal structure is confirmed using X-ray diffraction and transmission electron microscopy. Scanning electron microscopy and energy-dispersive X-ray spectroscopy are used to gain insight into the vapor-solid growth mechanism. The role of group II and V elements is reversed in contrast to III-V and other II-V systems, and the tips are found to be As-rich.

show abstract

“…However, the low frequency parts of the two RS spectra should be due to modes with predominant Zn contribution involved. This corresponds quite well with the mode frequency values observed for Cd,As, [7] and Zn,As, [8] crystals in which Cd(Zn)-As bonds exist only, as well as those for tetragonal ZnP, [5] (with spiral P chains). However, further studies both theoretical and experimental are needed for a better understanding of the lattice dynamics of monoclinic ZnAs,.…”

Section: Discussionsupporting

confidence: 86%

Raman Scattering in ZnAs₂ Monoclinic Crystals

Weszka

Bałkanski

Jouanne

et al. 1992

Physica Status Solidi (b)

Self Cite

View full text Add to dashboard Cite

Raman scattering in ZnAs, monoclinic crystals is studied at room temperature in backward geometry. Features within the 190 to 270 cm-' frequency interval are due to As-chain modes. Low frequency features within the 10 to 100 cm-' area are attributed to modes with considerable contribution from Zn atoms involved.La diffusion Raman dans les cristaux monocliniques du ZnAs, a etC ktudiee a la temperature ambiante. Les bandes dans l'interval 190 a 270 cm-' sont attributes aux modes des helices d'atomes d'As. Celles aux basses frequences dans I'interval 10 a 100 cm-' sont attributuees aux modes avec une contribution importante des atomes du Zn.

show abstract

Some aspects of raman scattering in Cd₃As₂ single crystals

Cited by 19 publications

References 11 publications

Large Thermopower, Crystalline Cd₃As₂ by Low‐Temperature Vapor Deposition for Room Temperature Heat Waste Recovery

Large Thermopower, Crystalline Cd₃As₂ by Low‐Temperature Vapor Deposition for Room Temperature Heat Waste Recovery

Structural properties and growth mechanism of Cd3As2 nanowires

Raman Scattering in ZnAs₂ Monoclinic Crystals

Contact Info

Product

Resources

About

Some aspects of raman scattering in Cd3As2 single crystals

Cited by 19 publications

References 11 publications

Large Thermopower, Crystalline Cd3As2 by Low‐Temperature Vapor Deposition for Room Temperature Heat Waste Recovery

Large Thermopower, Crystalline Cd3As2 by Low‐Temperature Vapor Deposition for Room Temperature Heat Waste Recovery

Structural properties and growth mechanism of Cd3As2 nanowires

Raman Scattering in ZnAs2 Monoclinic Crystals

Contact Info

Product

Resources

About

Some aspects of raman scattering in Cd₃As₂ single crystals

Large Thermopower, Crystalline Cd₃As₂ by Low‐Temperature Vapor Deposition for Room Temperature Heat Waste Recovery

Large Thermopower, Crystalline Cd₃As₂ by Low‐Temperature Vapor Deposition for Room Temperature Heat Waste Recovery

Raman Scattering in ZnAs₂ Monoclinic Crystals