A one-dimensional Fickian model to predict the Ga depth profiles in three-stage Cu(In,Ga)Se{sub 2}

Journal Article · Wed May 28 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4880298· OSTI ID:22304286

Mainz, R. ^[1]; Sadewasser, S. ^[2]

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1. Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, 14109 Berlin (Germany)
2. International Iberian Nanotechnology Laboratory, Avenida Mestre Jose Veiga s/n, 4715-330 Braga (Portugal)

We present a one-dimensional Fickian model that predicts the formation of a double Ga gradient during the fabrication of Cu(In,Ga)Se{sub 2} thin films by three-stage thermal co-evaporation. The model is based on chemical reaction equations, structural data, and effective Ga diffusivities. In the model, the Cu(In,Ga)Se{sub 2} surface is depleted from Ga during the deposition of Cu-Se in the second deposition stage, leading to an accumulation of Ga near the back contact. During the third deposition stage, where In-Ga-Se is deposited at the surface, the atomic fluxes within the growing layer are inverted. This results in the formation of a double Ga gradient within the Cu(In,Ga)Se{sub 2} layer and reproduces experimentally observed Ga distributions. The final shape of the Ga depth profile strongly depends on the temperatures, times and deposition rates used. The model is used to evaluate possible paths to flatten the marked Ga depth profile that is obtained when depositing at low substrate temperatures. We conclude that inserting Ga during the second deposition stage is an effective way to achieve this.

• OSTI ID: 22304286
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 20; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHEMICAL REACTIONS
COMPUTERIZED SIMULATION
COPPER COMPOUNDS
DEPOSITION
DISTRIBUTION
EVAPORATION
FABRICATION
FICK LAWS
GALLIUM ADDITIONS
GALLIUM COMPOUNDS
INDIUM COMPOUNDS
LAYERS
ONE-DIMENSIONAL CALCULATIONS
SELENIUM COMPOUNDS
SPATIAL DISTRIBUTION
SUBSTRATES
SURFACES
THIN FILMS