CuInSe 2 phase formation during Cu2Se/In2Se3 interdiffusion reaction

Abstract

Diffusion couples based upon Cu 2 Se/In 2 Se 3 pairings have been examined in order to identify the kinetics of intermediate phase development and the associated phase equilibria. For the diffusion couples annealed at 550°C for 1.5 h, all phases included in the Cu 2 Se-In 2 Se 3 pseudobinary phase diagram section developed including the CuInSe 2 ͑CIS͒ phase. Also, the In 6 Se 7 phase formed for annealing times in excess of 1.5 h at 550°C, indicating a modification of the diffusion pathway outside the pseudobinary phase diagram section. The growth of the CIS phase formed by reactive diffusion follows parabolic kinetics (x 2 ϭkt) with the k value of 3.3ϫ10 Ϫ8 cm 2 /s. CIS phase precipitates with a dendritic morphology are also produced within the Cu 2 Se side of the diffusion couple far from the initial interface, indicating that In is the fast component during interdiffusion. Based upon electron diffraction analysis and simulation of electron diffraction patterns, the dendritic shaped CIS precipitate structure was uniquely determined to be the metastable zinc blende type rather than the stable chalcopyrite-type structure. The structure and orientation relationship between the metastable CIS phase and the Cu 2 Se matrix satisfy the conditions established for the development of a solid state dendritic morphology.

Chemical incorporation of copper into indium selenide thin‐films for processing of CuInSe2 solar cells

“…The diffuse boundary between the copper and indium selenide layers that is observed in the XPS data is attributed in part to these In atoms and in part to interpenetration of the layers along grain boundaries. β-Cu 2-x Se and γ-In 2 Se 3 have been observed to react directly to form CuInSe 2 at temperatures >425°C in investigations of stacked selenide thin-films and diffusion couples [26,27]. However, the Raman spectra and XRD diffractograms reported here for partially selenized samples indicate a change in the copper selenide phase from Cu 2-x Se to CuSe during selenization of our samples.…”

“…x Se exhibits high cationic conductivity and high In diffusion coefficients have been specifically observed in Cu 2-x Se [26], allowing the ion-exchange reaction to continue after the In 2 Se 3 surface is covered with Cu 2-x Se. Removal of the precursor layer from the hot CuSO 4 solution quenches the ion-exchange reaction, hence the Cu 2-x Se surface layer should contain a graded concentration of indium ions that were diffusing towards the surface.…”

Growth of Cu(In,Ga)Se2 thin films using ionization Ga source and application for solar cells

“…2(c), in addition with the typical diffraction planes of the α-CIGS phases, a characteristic peak of the Cu 2-X Se (002) phase was present. The existence of this binary phase was consistent with the phase diagram for such composition [10]. 2 , V OC = 516.7 mV, FF = 74.4%).…”

Development of thin‐film Cu(In,Ga)Se2and CdTe solar cells

“…This is attributed to the formation of a Cu x Se phase during the Cu-rich first stage, that improves the mobility of group III atoms during growth. [61][62][63] An 'inverse' two-stage process starts with a precursor layer that is more Cu-poor than the finished film. 64,65 The so-called three-stage process, introduced by NREL, 66 is obtained by starting the deposition with an (In,Ga) x Se y precursor, followed by the co-deposition of Cu and Se until Cu-rich overall composition is reached, and finally the overall Cu concentration is readjusted by subsequent deposition of In, Ga and Se.…”