High pressure sputtering of Mo targets in mixed Ar/O2/H2 atmospheres for hole selective contacts in photovoltaic cells

Abstract

We have deposited thin films of MoOx using highpressure sputtering (HPS) and Ar/O2/H2 atmospheres aiming at the compositional and interface control. We found that H2 impacts plasma composition, which in turn produces a reduction of the oxygen content and a change in the refractive index of the films. However, the presence of hydrogen in the plasma atmosphere enhances interfacial SiOx regrowth, as FTIR shows. TEM measurements show that this regrowth is not critical for thin films. Also, increasing the hydrogen ratio produces a change from amorphous to an amorphous/polycrystalline mixture. Lifetime measurements show that these films are adequate for their integration into test HIT-like structures, but require more work to produce competitive iVoc values.