Carrier polarity reversal with sodium addition in Bridgman-grown CuInSe2

Champness, C.H.; Myers, H.F.; Shih, I.

doi:10.1016/j.tsf.2010.12.040

Cited by 5 publications

(2 citation statements)

References 6 publications

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“…% (see Fig. 4) is consistent with non-detection of this element, reported in the present laboratory by EDX 21 and by Lyahovitskaya et al 29 using SIMS in bulk crystals.…”

Section: Discussionsupporting

confidence: 92%

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Relation between sodium addition and excess selenium in Bridgman-grown CuInSe 2

2011

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Ingots containing cm-sized monocrystals of CuInSe 2 have been grown in quartz ampoules by a vertical-Bridgman method. Included also in the ampoules were varying quantities of elemental Na, as well as excess Se above stoichiometry. Deposits were seen within the ampoules after growth, including a white deposit formed through a reaction of the Na with the quartz, and a reddish-brown deposit mostly containing Na and Se. Thermoelectric power measurements indicate that stoichiometric material grown with no excess Se and no Na is p-type. With the addition of Na above a critical amount to the ampoule, the resulting ingots were always n-type. This p to n conductivity type change is inhibited when excess Se is also present, and more Na is required for the change to occur. The critical amount of Na was found to be approximately twice the atomic amount of excess Se. XRD indicated that the chalcopyrite structure of the material was maintained with additions of up to 3 at. % Na, even as the material was changed from p-to n-type, and no sodium was detected in the bulk. It is suggested that a reaction between the Na and the Se occurs, resulting in the formation of Na 2 Se. The Se used in this reaction is therefore unable to be a part of the CuInSe 2 lattice, thereby increasing the number of donor-like Se vacancies, rendering it n-type. In this model, the addition of excess Se replaces those Se atoms which react with the Na, so that the material remains p-type.

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“…% (see Fig. 4) is consistent with non-detection of this element, reported in the present laboratory by EDX 21 and by Lyahovitskaya et al 29 using SIMS in bulk crystals.…”

Section: Discussionsupporting

confidence: 92%

“…In these cases, a reddish-brown deposit was found on the inside of the ampoule immediately adjacent to the ingot. This deposit was also analyzed by SEM-EDX and was found to contain all four starting elements, Cu, In, Se and Na, with the latter two comprising most of the deposit and the former two found in only trace amounts 21 .…”

Section: Growth Resultsmentioning

confidence: 99%

Relation between sodium addition and excess selenium in Bridgman-grown CuInSe 2

2011

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Electrical effect of introducing elemental sodium into the Bridgman melt of CuInSe2+x crystals

Myers¹,

Champness

Shih

2014

Journal of Crystal Growth

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Diffusion of sodium in single crystal CuInSe2

Forest

McCandless

et al. 2017

Journal of Applied Physics

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The incorporation of sodium from sodium fluoride in single-crystal CuInSe2 (CIS) is investigated to provide insight into the intra-granular aspects of sodium incorporation in CIS-based thin films. Sodium was incorporated by evaporating NaF onto two CIS crystals of varying compositions and defect structures followed by heating under vacuum. Diffusion profiles show a near-surface reaction before a deeper diffusion zone which follows a complementary error function, confirming Na diffusion into the crystals. Transmission electron microscopy analysis indicates that dislocations do not control the diffusion process. The activation energy of diffusion is ∼0.7 eV for both crystals. This low activation energy suggests that Na diffusion occurs rapidly through the bulk at temperatures as low as 300 °C and helps explain the uniform Na concentration often observed in grain interiors of polycrystalline Cu(InGa)Se2 thin films.

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Carrier polarity reversal with sodium addition in Bridgman-grown CuInSe2

Cited by 5 publications

References 6 publications

Relation between sodium addition and excess selenium in Bridgman-grown CuInSe 2

Relation between sodium addition and excess selenium in Bridgman-grown CuInSe 2

Electrical effect of introducing elemental sodium into the Bridgman melt of CuInSe2+x crystals

Diffusion of sodium in single crystal CuInSe2

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