Atomic layer deposition of Cu2S for future application in photovoltaics

Alternating exposure to bis(N,N′-di-sec-butylacetamidinato)dicopper(I) and hydrogen sulfide is shown to produce high quality chalcocite (Cu2S) thin films by atomic layer deposition on silicon and fused silica substrates. The layer-by-layer chemical vapor deposition method enables conformal growth of the phase-pure material at 130 °C. X-ray diffraction reveals that polycrystalline high-chalcocite films are deposited preferentially oriented in the ⟨00l⟩ plane. The optical properties of this naturally p-type absorber compare well with previous reports on single crystals, highlighting the applicability of the technique to nanostructured photovoltaics.