As Doping in (Hg,Cd)Te: An Alternative Point of View

Hails, Janet E.; Irvine, S.J.C.; Cole‐Hamilton, David J.; Giess, J.; Houlton, M. R.; Graham, Andrew

doi:10.1007/s11664-008-0452-1

Cited by 13 publications

(7 citation statements)

References 84 publications

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“…Experimental work has identified As as shallow acceptor 14 (<100 meV), but activation of As has been difficult 15 , 16 . High temperature post-growth annealing activation steps with optimized stoichiometry control are generally required to produce high concentrations of acceptors 17 , 18 . Although significant progress has been made, the success of As-doping is still limited because of the short carrier lifetime 16 .…”

Section: Introductionmentioning

confidence: 99%

Self-compensation in arsenic doping of CdTe

Ablekim

Swain

Yin

et al. 2017

Sci Rep

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Efficient p-type doping in CdTe has remained a critical challenge for decades, limiting the performance of CdTe-based semiconductor devices. Arsenic is a promising p-type dopant; however, reproducible doping with high concentration is difficult and carrier lifetime is low. We systematically studied defect structures in As-doped CdTe using high-purity single crystal wafers to investigate the mechanisms that limit p-type doping. Two As-doped CdTe with varying acceptor density and two undoped CdTe were grown in Cd-rich and Te-rich environments. The defect structures were investigated by thermoelectric-effect spectroscopy (TEES), and first-principles calculations were used for identifying and assigning the experimentally observed defects. Measurements revealed activation of As is very low in both As-doped samples with very short lifetimes indicating strong compensation and the presence of significant carrier trapping defects. Defect studies suggest two acceptors and one donor level were introduced by As doping with activation energies at ~88 meV, ~293 meV and ~377 meV. In particular, the peak shown at ~162 K in the TEES spectra is very prominent in both As-doped samples, indicating a signature of AX-center donors. The AX-centers are believed to be responsible for most of the compensation because of their low formation energy and very prominent peak intensity in TEES spectra.

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Section: Introductionmentioning

confidence: 99%

Self-compensation in arsenic doping of CdTe

Ablekim

Swain

Yin

et al. 2017

Sci Rep

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“…In addition, there have been recent reports of chemical vapor deposition (CVD)-grown HgCdTe:As that claim a very different scenario for the activation process. 12 In this work, EXAFS was used because of its ability to probe only one element (arsenic in our case) and to provide a very accurate determination of its environment in terms of the chemical nature of the neighbors, their numbers and distances with respect to the probed element. With this technique we were able to 'see' the environment of arsenic before and after thermal activation and, therefore, determine the mechanism of electrical activation.…”

Section: Introductionmentioning

confidence: 99%

Extended X-ray Absorption Fine Structure Investigation of Arsenic in HgCdTe: the Effect of the Activation Anneal

Ballet

Polge

Biquard

et al. 2009

Journal of Elec Materi

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Extended x-ray absorption fine structure (EXAFS) investigation was carried out on two arsenic-doped HgCdTe samples. Arsenic incorporation was achieved with a non-conventional radiofrequency plasma source in a molecular beam epitaxy reactor. Both samples were taken from the same epitaxial run. One of these samples followed a 400°C activation anneal under Hg pressure. EXAFS was used here to probe the local environment around arsenic, and the experimental data were fit through first-principle calculations to extract a quantitative description of the arsenic site transfer upon annealing. Arsenic neighbors are described in terms of chemical nature, numbers and distances. Arsenic was found to be involved mostly in noncrystalline structures, either an As 2 Te 3 glass or an AsHg compact structure. The effect of annealing is to break down the chalcogenide glass, thus favoring the compact AsHg structure. EXAFS results were compared to 77 K Halleffect measurements, and a very good correlation was found. These findings were compared to the commonly admitted scenario for arsenic site incorporation and transfer upon annealing and provided a new picture and the first experimental evidence of the site transfer.

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“…Experimental results show that higher hole density exceeding 10 16 =cm 3 indeed can be obtained with P or As doping. [23][24][25][26][27][28][29][30] Usually, the doping process is conducted using the standard quenching or annealing method and by quenching, the high activation of dopants is expected to be sustained. 16,31 However, several problems still remain unclear.…”

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confidence: 99%

Enhanced p-type dopability of P and As in CdTe using non-equilibrium thermal processing

Yang

Yin

Park

et al. 2015

Journal of Applied Physics

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One of the main limiting factors in CdTe solar cells is its low p-type dopability and, consequently, low open-circuit voltage (VOC). We have systematically studied P and As doping in CdTe with first-principles calculations in order to understand how to increase the hole density. We find that both P and As p-type doping are self-compensated by the formation of AX centers. More importantly, we find that although high-temperature growth is beneficial to obtain high hole density, rapid cooling is necessary to sustain the hole density and to lower the Fermi level close to the valence band maximum (VBM) at room temperature. Thermodynamic simulations suggest that by cooling CdTe from a high growth temperature to room temperature under Te-poor conditions and choosing an optimal dopant concentration of about 1018/cm3, P and As doping can reach a hole density above 1017/cm3 at room temperature and lower the Fermi level to within ∼0.1 eV above the VBM. These results suggest a promising pathway to improve the VOC and efficiency of CdTe solar cells.

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As Doping in (Hg,Cd)Te: An Alternative Point of View

Cited by 13 publications

References 84 publications

Self-compensation in arsenic doping of CdTe

Self-compensation in arsenic doping of CdTe

Extended X-ray Absorption Fine Structure Investigation of Arsenic in HgCdTe: the Effect of the Activation Anneal

Enhanced p-type dopability of P and As in CdTe using non-equilibrium thermal processing

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