Observation and first-principles calculation of buried wurtzite phases in zinc-blende CdTe thin films

Yan, Y.; Al‐Jassim, M. M.; Jones, K. M.; Wei, Su‐Huai; Zhang, Shou-Cheng

doi:10.1063/1.1308062

Cited by 60 publications

(44 citation statements)

References 14 publications

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“…A polycrystalline network with hexagonal geometry and equal mixture of zb and wz grains is present at the interface with an average grain size of ~15 Å as shown in Figure 5(c). This is anticipated since the CdS substrate has a hexagonal surface geometry and experimental growths on this surface geometry commonly report polytypism (Smith et al, 2000) (Al-Jassim et al, 2001) (Yan et al, 2000). However only ~80 Å away from the interface, the hexagonal geometry is replaced by much larger zb and wz grains of ~80 Å nominal size and no remnant of the underlying hexagonal geometry ( Figure 5(d)).…”

Section: Lattice Structure Morphologymentioning

confidence: 90%

“…The lattice structure analyses results in Figure 1(a) show that each film contained multiple phase domains, having some amount of atoms associated to wurtzite and zinc blende structures. This polytypism is a common occurrence reported in CdTe films grown using MBE (Smith et al, 2000), as well as epitaxy using CSS (Al-Jassim et al, 2001) (Yan et al, 2000). Each simulated film also contained some regions where the structure did not match either the wz or zb lattice structures (unmatched percentages are not shown in the figure).…”

Section: Analysis Of MD Datamentioning

confidence: 97%

“…This occurs in defected regions such as point defects (e.g., vacancies and interstitials), surfaces, grain boundaries, and dislocation cores. (Yan et al, 2000) and stacking faults along a direction about ~22° from the interface plane. The majority of the grains have a zinc blende crystal structure.…”

Section: Lattice Structure Morphologymentioning

confidence: 99%

See 2 more Smart Citations

Molecular Dynamics Simulations of CdTe / CdS Heteroepitaxy - Effect of Substrate Orientation

Chavez¹,

Zhou²,

Almeida³

et al. 2016

JMSR

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Molecular dynamics simulations were used to catalogue atomic scale structures of CdTe films grown on eight wurtzite (wz) and zinc-blende (zb) CdS surfaces. Polytypism, grain boundaries, dislocations and other film defects were detected. Dislocation lines were distributed in three distinct ways. For the growths on the wz {0001} and zb {111} surfaces, dislocations were found throughout the epilayers and formed a network at the interface. The dislocations within the films grown on the wz {1 100}, wz {112 0}, zb {1 10}, zb {010}, and zb { 1 } surfaces formed an interface network and also threaded from the interface towards the film's surface. In contrast, the growth on the zb {112 } surface only had dislocations localized to the interface. This film exhibited a different orientation from the substrate to reduce the lattice mismatch strain energies, and therefore, its misfit dislocation density. Our study indicates that the substrate orientation could be utilized to modify the morphology of dislocation networks in lattice mismatched multi-layered systems.

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Section: Lattice Structure Morphologymentioning

confidence: 90%

Section: Analysis Of MD Datamentioning

confidence: 97%

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Molecular Dynamics Simulations of CdTe / CdS Heteroepitaxy - Effect of Substrate Orientation

Chavez¹,

Zhou²,

Almeida³

et al. 2016

JMSR

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“…ZnO, in thin film or nanostructure form, often contains stacking faults where both wurtzite and zinc blende phases are observed. Other materials with similar crystal structures, such as CdTe, exhibit similar stacking faults and twin boundaries where the wurtzite and zinc blende phases form side by side [22,23]. Planar defects can significantly affect the electronic properties of nanowires [24].…”

Section: Introductionmentioning

confidence: 99%

Modelling the growth of ZnO thin films by PVD methods and the effects of post-annealing

Blackwell

Smith

Kenny

et al. 2013

J. Phys.: Condens. Matter

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Results are presented for modelling of the evaporation and magnetron sputter deposition of Zn x O y onto an O-terminated ZnO (000 1) wurtzite surface. Growth was simulated through a combination of molecular dynamics (MD) and an on-the-fly kinetic Monte Carlo (otf-KMC) method, which finds diffusion pathways and barriers without prior knowledge of transitions. We examine the effects of varying experimental parameters, such as substrate bias, distribution of the deposition species and annealing temperature. It was found when comparing evaporation and sputtering growth that the latter process results in a denser and more crystalline structure, due to the higher deposition energy of the arriving species. The evaporation growth also exhibits more stacking faults than the sputtered growth. Post-annealing at 770 K did not allow complete recrystallization, resulting in films which still had stacking faults where monolayers formed in the zinc blende phase, whereas annealing at 920 K enabled the complete recrystallization of some films to the wurtzite structure. At the latter temperature atoms could also sometimes be locked in the zinc blende phase after annealing. When full recrystallization did not take place, both wurtzite and zinc blende phases were seen in the same layer, resulting in a phase boundary. Investigation of the various distributions of deposition species showed that, during evaporation, the best quality film resulted from a stoichiometric distribution where only ZnO clusters were deposited. During sputtering, however, the best quality film resulted from a slightly O rich distribution. Two stoichiometric distributions, one involving mainly ZnO clusters and the other involving mainly single species, showed that the distribution of deposition species makes a huge impact on the grown film. The deposition of predominantly single species causes many more O atoms at the surface to be sputtered or reflected, resulting in an O deficiency of up to 18% in the deposited film and therefore resulting in more stacking faults and phase boundaries. The methods used allow analysis of key mechanisms that occur during the growth process and give hints as to the optimum conditions under which complete crystalline layers can form.

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“…The presence of a local wurtzite crystal structure is synonymous with stacking faults which result in poor electrical quality. 51 Figure 6 clearly shows the ability of LA to reduce the presence of the wurtzite phase and the extended defects associated with it: the wurtzite peaks decrease in intensity and the zincblende peaks become narrower upon LA.…”

Section: Laser Processing For Bulk Effects In Cdtementioning

confidence: 99%

Laser processing for thin film chalcogenide photovoltaics: a review and prospectus

et al. 2015

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Abstract. We review prior and on-going works in using laser annealing (LA) techniques in the development of chalcogenide-based [CdTe and CuðIn; GaÞðS; SeÞ 2 ] solar cells. LA can achieve unique processing regimes as the wavelength and pulse duration can be chosen to selectively heat particular layers of a thin film solar cell or even particular regions within a single layer. Pulsed LA, in particular, can achieve non-steady-state conditions that allow for stoichiometry control by preferential evaporation, which has been utilized in CdTe solar cells to create Ohmic back contacts. Pulsed lasers have also been used with CuðIn; GaÞðS; SeÞ 2 to improve device performance by surface-defect annealing as well as bulk deep-defect annealing. Continuouswave LA shows promise for use as a replacement for furnace annealing as it almost instantaneously supplies heat to the absorbing film without wasting time or energy to bring the much thicker substrate to temperature. Optimizing and utilizing such a technology would allow production lines to increase throughput and thus manufacturing capacity. Lasers have also been used to create potentially low-cost chalcogenide thin films from precursors, which is also reviewed. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Observation and first-principles calculation of buried wurtzite phases in zinc-blende CdTe thin films

Cited by 60 publications

References 14 publications

Molecular Dynamics Simulations of CdTe / CdS Heteroepitaxy - Effect of Substrate Orientation

Molecular Dynamics Simulations of CdTe / CdS Heteroepitaxy - Effect of Substrate Orientation

Modelling the growth of ZnO thin films by PVD methods and the effects of post-annealing

Laser processing for thin film chalcogenide photovoltaics: a review and prospectus

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