Wafer-Scale Pulsed Laser Deposition of ITO for Silicon Heterojunction Solar Cells: Reduced Damage vs Interfacial Resistance

Abstract

Pulsed laser deposition (PLD) has been recently proposed as an alternative low-damage physical vapor deposition technique to deposit Transparent Conducting Oxides (TCOs) onto sensitive functional layers such as required in various solar cells. Here we studied the role of deposition pressure during PLD of TCO with identical sheet resistance (60 Ω/) on final silicon heterojunction (SHJ) solar cell performance. Solar cells with PLD Sn-doped In2O3 (ITO) at all conditions maintained high passivation quality but increased pressures lead to high series resistance. Transmission electron microscopy spectrometry revealed the formation of a parasitic SiOx at the ITO/a-Si:H interface of the SHJ cell causing a transport barrier. The optimized ITO films with highest carrier density allows obtaining SHJ efficiency >21% with 75-nm-thick PLD ITO. We furthermore demonstrate high efficiency SHJ cells (>22%) with reduced indium consumption by combining an optimized thin ITO film by PLD and a TiOx capping layer.