Properties of Cu(In,Ga)Se₂ Thin Films Prepared by Chemical Spray Pyrolysis

Abstract

Thin polycrystalline films of Cu(In,Ga)Se2 alloy with the single-phase chalcopyrite structure were successfully grown by the chemical spray pyrolysis (CSP) method on a glass substrate at 360 and 400°C. Alloy composition in the film was well controlled by that in the spray solution. The films were characterized by X-ray diffraction, optical absorption, Raman spectroscopy, van der Pauw measurement and scanning electron microscopy. It was found that lattice constants, the optical band-gap energy and the A 1 mode phonon frequency changed continuously with the alloy composition x. A grain size of about 1 µm was obtained for Cu-rich films.

Structural and optical properties of thin films of Cu(In,Ga)Se2 semiconductor compounds

“…should be noted that our deflection coefficient b ≈ 0.13 eV at 4.2 K is the lowest of the known values for films and monocrystals of CIGS; this indicates growth of relatively high quality films in which the effects of a chaotic distribution of the components of the compound shows up no more strongly than in the earlier papers [20][21][22][23].…”

Structural analysis of CIGS film prepared by chemical spray deposition

“…However, for SP CIGS films A1-peak-increase is fitted rather with x 2 , especially in small Ga contents. Up to now, linear fitting [12] and quadratic fitting [13,14] were applied to A1 mode shift with x. Elucidation of which fitting is more accurate is out of scope of this paper. It is also noted that the frequency of A1 mode for SP CIGS film (x ¼ 0) is measured to be 168.5 cm À1 , which is smaller than 172 cm À1 [12], 173 cm À1 [13], 174 cm À1 [14,15], 175 cm À1 [16] reported by others.…”

“…Up to now, linear fitting [12] and quadratic fitting [13,14] were applied to A1 mode shift with x. Elucidation of which fitting is more accurate is out of scope of this paper. It is also noted that the frequency of A1 mode for SP CIGS film (x ¼ 0) is measured to be 168.5 cm À1 , which is smaller than 172 cm À1 [12], 173 cm À1 [13], 174 cm À1 [14,15], 175 cm À1 [16] reported by others. When the substrate temperature is low during spray of CuInS 2 [17] or Cu 2 ZnSnS 4 [18], the as-deposited film shows A1 peak at lower frequency.…”

Deposition and characterization of graded Cu(In1-xGax)Se2 thin films by spray pyrolysis

“…The effects of T s , pH and R on CIS and CIGS thin films using CSP were investigated by several authors [18,19,21,25,27,34]. Based on their investigations we have synthesized CIGS thin films at different T s ranging from 250 to 400 C and determined the optimum value of 350 C to obtain single phase CIGS thin film on the basis of following characterizations.…”