Role of quantum confinement in giving rise to high electron mobility in GaN nanowall networks

Bhasker, H. P.; Thakur, Varun; Shivaprasad, S. M.; Dhar, Subhabrata

doi:10.1016/j.ssc.2015.07.008

Cited by 16 publications

(9 citation statements)

References 12 publications

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“…The study further predicts a very high electron mobility in this channel [16]. This prediction is also consistent with the experimental observation of high conductivity [17][18][19][20] and long phase coherence length [18,21,22] of electrons in the networks of wedge-shaped c-oriented GaN nanowalls. It will be interesting to understand the mechanism of spin transport through this channel.…”

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confidence: 89%

Polarization induced two dimensional confinement of carriers in wedge shaped polar semiconductors

Deb

Bhasker

Thakur

et al. 2016

Sci Rep

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A novel route to achieve two dimensional (2D) carrier confinement in a wedge shaped wall structure made of a polar semiconductor has been demonstrated theoretically. Tapering of the wall along the direction of the spontaneous polarization leads to the development of charges of equal polarity on the two inclined facades of the wall. Polarization induced negative (positive) charges on the facades can push the electrons (holes) inward for a n-type (p-type) material which results in the formation of a 2D electron (hole) gas at the central plane and ionized donors (acceptors) at the outer edges of the wall. The theory shows that this unique mode of 2D carrier confinement can indeed lead to a significant enhancement of carrier mobility. It has been found that the reduced dimensionality is not the only cause for the enhancement of mobility in this case. Ionized impurity scattering, which is one of the major contributer to carrier scattering, is significantly suppressed as the carriers are naturally separated from the ionized centers. A recent experimental finding of very high electron mobility in wedge shaped GaN nanowall networks has been analyzed in the light of this theoretical reckoning.

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supporting

confidence: 89%

Polarization induced two dimensional confinement of carriers in wedge shaped polar semiconductors

Deb

Bhasker

Thakur

et al. 2016

Sci Rep

Self Cite

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“…Thus, the E B of the SLM sample was smaller. In addition, the natural superlattices formed by the bilayer and split structures close to the TB might increase carrier mobility due to the quantum confinement effect . Kim et al also predicted that the carrier mobility could be increased by the arrangement of TB, which was similar to the high mobility phenomenon in two-dimensional electron gases .…”

Section: Resultsmentioning

confidence: 95%

“…Previous reports have shown that the seven-lamellar structure exhibits superlattice-like effects close to TB, which may also increase carrier mobility and decrease κ L . 31,32 The reason for the formation of these nanotwins is mainly attributed to the inherently low layer fault energy of the Bi 2 Te 3 material (46 mJ m −2 ). 33 This phenomenon tends to induce the formation of planar defects inside the crystal, especially in the case of a large temperature gradient in SLM.…”

Section: Resultsmentioning

confidence: 99%

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi₂Te_2.7Se_0.3 by 3D Printing-Driven Defect Engineering

Luo

Guo

et al. 2022

ACS Appl. Mater. Interfaces

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High-energy-conversion Bi 2 Te 3 -based thermoelectric generators (TEGs) are needed to ensure that the assembled material has a high value of average figure of merit (ZT ave ). However, the inferior ZT ave of the n-type leg severely restricts the large-scale applications of Bi 2 Te 3 -based TEGs. In this study, we achieved and reported a high peak ZT (1.33) of three-dimensional (3D)printing n-type Bi 2 Te 2.7 Se 0.3 . In addition, a superior ZT ave of 1.23 at a temperature ranging from 300 to 500 K was achieved. The high value of ZT ave was obtained by synergistically optimizing the electronic-and phonon-transport properties using the 3D-printing-driven defect engineering. The nonequilibrium solidification mechanism facilitated the multiscale defects formed during the 3D-printed process. Among the defects formed, the nanotwins triggered the energy-filtering effect, thus enhancing the Seebeck coefficient at a temperature range of 300−500 K. The effective scattering of wide-frequency phonons by multiscale defects reduced the lattice thermal conductivity close to the theoretical minimum of ∼0.35 W m −1 k −1 . Given the advantages of 3D printing in freeform device shapes, we assembled and measured bionic honeycombshaped single-leg TEGs, exhibiting a record-high energy conversion efficiency (10.2%). This work demonstrates the great potential of defect engineering driven by selective laser melting 3D-printing technology for the rational design of advanced n-type Bi 2 Te 2.7 Se 0.3 thermoelectric material.

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“…Computational Details; Bader charges for primitive cells (Table ST.1); concentration, atomic volume, bowing, fundamental, and direct band gaps for the primitive cells (Tables ST. 2 and ST.3); concentration and atomic volume for the supercells (Tables ST. 4 and ST.5); concentration, bowing, direct, and fundamental band gaps for the supercells (Tables ST.6−ST.13); mixing energies at each concentration for the supercells (Tables ST. 14…”

Section: ■ Dedicationmentioning

confidence: 99%

Electronic Properties of Zn₂V_(1–x)Nb_xN₃ Alloys to Model Novel Materials for Light-Emitting Diodes

Stratulat,

Tantardini,

Azizi

et al. 2023

J. Phys. Chem. Lett.

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We propose the Zn2V(1–x)Nb x N3 alloy as a new promising material for optoelectronic applications, in particular for light-emitting diodes (LEDs). We perform accurate electronic-structure calculations of the alloy for several concentrations x using density-functional theory with meta-GGA exchange–correlation functional TB09. The band gap is found to vary between 2.2 and 2.9 eV with varying V/Nb concentration. This range is suitable for developing bright LEDs with tunable band gap as potential replacements for the more expensive Ga(1–x)In(x)N systems. Effects of configurational disorder are taken into account by explicitly considering all possible distributions of the metal ions within the metal sublattice for the chosen supercells. We have evaluated the band gap’s nonlinear behavior (bowing) with variation of V/Nb concentration for two possible scenarios: (i) only the structure with the lowest total energy is present at each concentration and (ii) the structure with minimum band gap is present at each concentration, which corresponds to experimental conditions when also metastable structures are presents. We found that the bowing is about twice larger in the latter case. However, in both cases, the bowing parameter is found to be lower than 1 eV, which is about twice smaller than that in the widely used Ga(1–x)In(x)N alloy. Furthermore, we found that both crystal volume changes due to alloying and local effects (atomic relaxation and the V–N/Nb–N bonding difference) have important contributions to the band gap bowing in Zn2V(1–x)Nb x N3.

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Role of quantum confinement in giving rise to high electron mobility in GaN nanowall networks

Cited by 16 publications

References 12 publications

Polarization induced two dimensional confinement of carriers in wedge shaped polar semiconductors

Polarization induced two dimensional confinement of carriers in wedge shaped polar semiconductors

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi₂Te_2.7Se_0.3 by 3D Printing-Driven Defect Engineering

Electronic Properties of Zn₂V_(1–x)Nb_xN₃ Alloys to Model Novel Materials for Light-Emitting Diodes

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Role of quantum confinement in giving rise to high electron mobility in GaN nanowall networks

Cited by 16 publications

References 12 publications

Polarization induced two dimensional confinement of carriers in wedge shaped polar semiconductors

Polarization induced two dimensional confinement of carriers in wedge shaped polar semiconductors

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi2Te2.7Se0.3 by 3D Printing-Driven Defect Engineering

Electronic Properties of Zn2V(1–x)NbxN3 Alloys to Model Novel Materials for Light-Emitting Diodes

Contact Info

Product

Resources

About

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi₂Te_2.7Se_0.3 by 3D Printing-Driven Defect Engineering

Electronic Properties of Zn₂V_(1–x)Nb_xN₃ Alloys to Model Novel Materials for Light-Emitting Diodes