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

Abstract

Cu(In,Ga)Se2(CIGS) thin films with lower (Ga/III = 0.30) and higher (Ga/III = 0.70) Ga‐content were grown onto the soda‐lime glass substrates by the co‐evaporation process using ionization Ga source. The enlargement of grain size for the as‐grown CIGS films was observed using the higher grid ionization voltage (Vc) and filament current (Ifila). XRD results revealed that the crystal quality can be improved using higher Vc and Ifila which is consistent with SEM results. Hall effect measurements showed that an obvious increasing in carrier concentration and decreasing in resistivity using higher Vc. Finally, the lower and higher Ga‐content CIGS solar cell with a promising efficiency of 15.4% and 8.27% has been achieved, respectively. Our results suggested that the high energy inherent to the ionized Ga atoms could be transferred to the substrate and played an important role for improvement of film quality like a local substrate heating sources. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

An investigation into the effects of band gap and doping concentration on Cu(In,Ga)Se2 solar cell efficiency

“…The values of energy band gap and electron affinity are varied due to the change in Ga/(In+Ga) ratios. The Table 3 shows the variation in band gap along with electron affinity of Cu(In 1−x Ga x )Se 2 layer with respect to the variation in “x” (Song et al 2004 ; Klein et al 1996 ; Dejene 2009 ; Johnson 2004 ; Li et al 2009 ; Minemoto et al 2001 ; Gloeckler and Sites 2005 ; Černivec et al 2007 ) which can successively be plotted through curve fitting as shown in Fig. 2 .…”