High Mobility Transparent Conductive Oxides for Silicon Heterojunction Solar Cells Deposited by Rotatable Magnetrons

Sputtered indium tin oxide ITO is a widespread used material for application as transparent conducting oxide as the front contact of rear junction silicon heterojunction solar cells. Standard ITO films suffer from too high parasitic absorption in both the short and the long wavelength range. The aim of this contribution is to investigate lower absorbing TCOs deposited with industrial DC sputtering from rotatable targets. High Voc values gt;735 mV demonstrate that in spite of the high power industrial DC sputter process no significant sputter damage is observed, independent of the target material. Cell efficiencies up to 23.3 are obtained with titanium doped ITiO and tin doped indium oxide ITO 99 1 . The highest short circuit current values of 39.6 mA cm2 are reached with an ultimately low carrier and high mobility indium oxide based material. The cell efficiency in this case, however, is over compensated by a too low FF, mostly due to a higher contact resistivity and TCO sheet resistances. We ascribe this effect to the very low carrier concentratio