Dependence of the Minority-Carrier Lifetime on the Stoichiometry of CdTe Using Time-Resolved Photoluminescence and First-Principles Calculations

Ma, Jie; Kuciauskas, Darius; Albin, David S.; Bhattacharya, R. N.; Reese, Matthew O.; Barnes, Teresa M.; Li, Jian V.; Gessert, T. A.; Wei, Su‐Huai

doi:10.1103/physrevlett.111.067402

Cited by 129 publications

(86 citation statements)

References 42 publications

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“…Recently, Ma et al reported that growth of CdTe under Cd-rich conditions are beneficial to improve the device performance. 6 The migration behavior of Cd and Te on the CdTe (001) surface was reported by A.E. Patrakov and the results showed that at any position of the surface, Te adsorption is found to be stronger than that of Cd.…”

Section: Introductionmentioning

confidence: 89%

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Diffusion of Cd and Te adatoms on CdTe(111) surfaces: A computational study using density functional theory

et al. 2015

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ARTICLES YOU MAY BE INTERESTED INA computational ab initio study of surface diffusion of sulfur on the CdTe (111) CdTe is one of the most promising semiconductor for thin-film based solar cells. Here we report a computational study of Cd and Te adatom diffusion on the CdTe (111) A-type (Cd terminated) and B-type (Te terminated) surfaces and their migration paths. The atomic and electronic structure calculations are performed under the DFT formalism and climbing Nudge Elastic Band (cNEB) method has been applied to evaluate the potential barrier of the Te and Cd diffusion. In general the minimum energy site on the surface is labeled as A a site. In case of Te and Cd on B-type surface, the sub-surface site (a site just below the top surface) is very close in energy to the A site. This is responsible for the subsurface accumulation of adatoms and therefore, expected to influence the defect formation during growth. The diffusion process of adatoms is considered from A a (occupied) to A a (empty) site at the nearest distance. We have explored three possible migration paths for the adatom diffusion. The adatom surface interaction is highly dependent on the type of the surface. Typically, Te interaction with both type (5.2 eV for A-type and 3.8 eV for B-type) is stronger than Cd interactions(2.4 eV for B-type and 0.39 eV for A-type). Cd interaction with the A-type surface is very weak. The distinct behavior of the A-type and B-type surfaces perceived in our study explain the need of maintaining the A-type surface during growth for smooth and stoichiometric growth. C

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Section: Introductionmentioning

confidence: 89%

“…The strong E b on the surface and relatively low barrier potential allows the trapping and accumulation of the Te atoms on the surface. This will result in to poor morphology of the B-type surface [31][32][33]5,6 . We discuss these implications in the discussion section.…”

Section: Resultsmentioning

confidence: 99%

Diffusion of Cd and Te adatoms on CdTe(111) surfaces: A computational study using density functional theory

et al. 2015

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“…Previous calculations and experiments indicate that vacancies have lower formation energy than interstitials or antisites, and they can remain after samples are cooled, so vacancies are more likely to influence hole density. 19,20 After the Te anneal, a 1.54-1.55-eV peak emerges in the low-temperature PL data that have been identified as a donor-acceptor pair (DAP) transition involving an acceptor Cd-vacancy complex. [21][22][23][24] 116102 When samples are annealed in Te with Cu present, Cu can occupy Cd sites to form Cu Cd acceptors.…”

Section: 15mentioning

confidence: 99%

Carrier density and lifetime for different dopants in single-crystal and polycrystalline CdTe

et al. 2016

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CdTe defect chemistry is adjusted by annealing samples with excess Cd or Te vapor with and without extrinsic dopants. We observe that Group I (Cu and Na) elements can increase hole density above 1016 cm−3, but compromise lifetime and stability. By post-deposition incorporation of a Group V dopant (P) in a Cd-rich ambient, lifetimes of 30 ns with 1016 cm−3 hole density are achieved in single-crystal and polycrystalline CdTe without CdCl2 or Cu. Furthermore, phosphorus doping appears to be thermally stable. This combination of long lifetime, high carrier concentration, and improved stability can help overcome historic barriers for CdTe solar cell development.

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“…The absorption of a single photon is sufficient to generate an electron-hole pair which leads to carrier generation that decays exponentially away from the sample surface. A second route taken in [1]- [2] uses photons with energy smaller than the semiconductor bandgap, that is in a spectral range where the material is normally transparent. The generation of an electron-hole pair now requires the absorption of two photons.…”

Section: Introductionmentioning

confidence: 99%

Minority-carrier dynamics in semiconductors probed by two-photon microscopy

Gaury

Haney

2016

2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)

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Abstract-Two-photon time-resolved photoluminescence has been recently applied to various semiconductor devices to determine carrier lifetime and surface recombination velocities. So far the theoretical modeling activity has been mainly limited to the commonly used one-photon counterpart of the technique. Here we provide the analytical solution to a 3D diffusion equation that describes two-photon microscopy in the low-injection regime. We focus on a system with a single buried interface with enhanced recombination, and analyze how transport, bulk and surface recombinations influence photoluminescence decays. We find that bulk measurements are dominated by diffusion at short times and by bulk recombination at long times. Surface recombination modifies bulk signals when the optical spot is less than a diffusion length away from the probed interface. In addition, the resolution is increased as the spot size is reduced, which however makes the signal more sensitive to diffusion.Index Terms-Two-photon microscopy, carrier lifetime, surface recombination velocity.

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Dependence of the Minority-Carrier Lifetime on the Stoichiometry of CdTe Using Time-Resolved Photoluminescence and First-Principles Calculations

Cited by 129 publications

References 42 publications

Diffusion of Cd and Te adatoms on CdTe(111) surfaces: A computational study using density functional theory

Diffusion of Cd and Te adatoms on CdTe(111) surfaces: A computational study using density functional theory

Carrier density and lifetime for different dopants in single-crystal and polycrystalline CdTe

Minority-carrier dynamics in semiconductors probed by two-photon microscopy

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