Growth and characterization of Arsenic doped CdTe single crystals grown by Cd-solvent traveling-heater method

Nagaoka, Akinobu; Han, Kyu Bum; Misra, Sudhajit; Wilenski, Thomas; Sparks, Taylor D.; Scarpulla, Michael A.

doi:10.1016/j.jcrysgro.2017.03.002

Cited by 21 publications

(11 citation statements)

References 32 publications

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“…[16][17][18][19] Group-V elements, on the other hand, are natural substitutes for tellurium and are also expected to introduce shallow acceptor levels in CdTe. Recent experimental works suggest that doping with group-V elements under Cd-rich conditions can indeed increase the hole concentrations, 11,20,21 but also reveal the existence of an apparent doping limit. 21 The origin of this limiting mechanism is not well understood, but recent theoretical studies suggest that it is due to the formation of self-compensating positive charged AX centers.…”

Section: Introductionmentioning

confidence: 99%

“…Recent experimental works suggest that doping with group-V elements under Cd-rich conditions can indeed increase the hole concentrations, 11,20,21 but also reveal the existence of an apparent doping limit. 21 The origin of this limiting mechanism is not well understood, but recent theoretical studies suggest that it is due to the formation of self-compensating positive charged AX centers. 11,[22][23][24] In this work, we investigate the origin the p-type doping difficulties in phosphorus-doped CdTe.…”

Section: Introductionmentioning

confidence: 99%

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Self-compensation in phosphorus-doped CdTe

2017

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We investigate the self-compensation mechanism in phosphorus-doped CdTe. The formation energies, charge transition levels, and defects states of several P-related point defects susceptible to cause self-compensation are addressed by first-principles calculations. Moreover, we assess the influence of the spin-orbit coupling and supercell-size effects on the stability of AX centers donors, which are believed to be responsible for most of the self-compensation. We report an improved result for the lowest-energy configuration of the P interstitial (Pi) and find that the self-compensation mechanism is not due to the formation of AX centers. Under Te-rich growth conditions, (Pi) exhibits a formation energy lower than the substitutional acceptor (PTe) when the Fermi level is near the valence band, acting as compensating donor. While, for Cd-rich growth conditions, our results suggest that p-type doping is limited by the formation of (PTe − VTe) complexes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self-compensation in phosphorus-doped CdTe

2017

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“…Single crystals are ideal model systems for understanding doping, recombination, and transport, and substantial effort has been applied to grow As-doped single crystals and incorporate them into solar cells 5 , 15 . Nagaoka et al developed CdTe single-crystal growth using the traveling heater method (THM) 16 and reported mobilities and carrier lifetimes, and they achieved very high dopant activation in THM single-crystal CdTe 17 , 18 . THM growth is slow, and it is only possible for small crystals.…”

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confidence: 99%

Impact of dopant-induced band tails on optical spectra, charge carrier transport, and dynamics in single-crystal CdTe

Ščajev

Mekys

Subačius

et al. 2022

Sci Rep

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Cadmium telluride (CdTe) semiconductors are used in thin-film photovoltaics, detectors, and other optoelectronic applications. For all technologies, higher efficiency and sensitivity are achieved with reduced charge carrier recombination. In this study, we use state-of-the-art CdTe single crystals and electro-optical measurements to develop a detailed understanding of recombination rate dependence on excitation and temperature in CdTe. We study recombination and carrier dynamics in high-resistivity (undoped) and arsenic (As)-doped CdTe by employing absorption, the Hall effect, time-resolved photoluminescence, and pump-probe in the 80–600 K temperature range. We report extraordinarily long lifetimes (30 µs) at low temperatures in bulk undoped CdTe. Temperature dependencies of carrier density and mobility reveal ionization of the main acceptors and donors as well as dominant scattering by ionized impurities. We also distinguish different recombination defects. In particular, shallow AsTe and deep VCd−AsCd acceptors were responsible for p-type conductivity. AX donors were responsible for electron capture, while nonradiative recombination centers (VCd−AsTe, As2 precipitates), and native defects (VCd−TeCd) were found to be dominant in p-type and n-type CdTe, respectively. Bimolecular and surface recombination rate temperature dependencies were also revealed, with bimolecular coefficient T−3/2 temperature dependence and 170 meV effective surface barrier, leading to an increase in surface recombination velocity at high temperatures and excitations. The results of this study allowed us to conclude that enhanced crucible rotation growth of As-doped CdTe is advantageous to As activation, leading to longer lifetimes and larger mobilities and open-circuit voltages due to lower absorption and trapping.

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“…The stoichiometric feed polycrystalline CdTe 1Àx-Se x (x = 0-0.6) ingots weighed approximately 10-15 g. In our previous study, 19 Cd-rich CdTe single crystals were grown from 50 mol% Cd solvent at a growth temperature of 950°C through the three zones of the furnace. In this study, the THM growth temperature with increasing Se composition was increased to 1000°C because the melting point of CdTe 0.5 Se 0.5 is 20-30°C higher than that of CdTe.…”

Section: Structural Properties Of Cdte 12x Se Xmentioning

confidence: 99%

“…We have previously grown high-quality As-doped Cd-rich CdTe single crystals from metal Cd solvent near thermodynamic equilibrium using the traveling heater method (THM). 19 In this study, we investigated the growth of group-V doped Cd-rich CdTe 1Àx-Se x single crystals using the THM. It is now becoming clearer how the formation of the CdTe 1Àx-Se x alloy may affect the group-V doping and physical properties, and this report proposes some possible answers to these questions.…”

Section: Introductionmentioning

confidence: 99%

Growth and Characterization of Arsenic-Doped CdTe1−xSex Single Crystals Grown by the Cd-Solvent Traveling Heater Method

Nagaoka

Nishioka

Yoshino

et al. 2020

Journal of Elec Materi

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The photovoltaic performance of CdTe solar cells is mainly limited by low doping and short minority carrier lifetime. Group-V element doping and Sealloying have a significant impact on tuning these fundamental CdTe properties. In this paper, we report the growth of p-type As-doped, Cd-rich CdTe 1Àx Se x single crystals using metallic Cd as the solvent in the travelingheater method. The structural and electrical properties of CdTe 1Àx Se x are examined for different Se concentrations. CdTe 1Àx Se x single crystals (0 £ x £ 0.5) with zincblende structure indicate homogeneous composition. The 10 17 cm À3 As-doping activation efficiency can be maintained at close to 50% for x £ 0.2. Se alloying leads to bulk minority carrier lifetime exceeding 30 ns for samples doped near 10 17 cm À3. These results help us to overcome the current roadblocks in device performance.

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Growth and characterization of Arsenic doped CdTe single crystals grown by Cd-solvent traveling-heater method

Cited by 21 publications

References 32 publications

Self-compensation in phosphorus-doped CdTe

Self-compensation in phosphorus-doped CdTe

Impact of dopant-induced band tails on optical spectra, charge carrier transport, and dynamics in single-crystal CdTe

Growth and Characterization of Arsenic-Doped CdTe1−xSex Single Crystals Grown by the Cd-Solvent Traveling Heater Method

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