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 MoO x using high-pressure sputtering (HPS) and Ar/O 2 /H 2 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 SiO x 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.