Atomic layer deposition of metal sulfide thin films using non-halogenated precursors

A method for preparing a Cu2S film on a substrate, comprising:

• providing an atomic layer deposition (ALD) reactor;
• providing a substrate;
• providing a first non-halogenated precursor, the first precursor comprising Bis(N,N′-di-sec-butylacetamidinato)dicopper(I);
• providing a second non-halogenated precursor, the second precursor comprising H2S;
• heating the substrate to a reaction temperature;
• exposing the substrate in the ALD reactor to the first non-halogenated precursor for a first predetermined duration;
• exposing the substrate in the ALD reactor to the second non-halogenated precursor for a second predetermined duration;
• repeating for a predetermined number of cycles exposure of the substrate in the ALD reactor to the first non-halogenated precursor and the second non-halogenated precursor to form a Cu2S film on the substrate.

A method for preparing a portion of an interdigitated photovoltaic device, comprising:

• providing an atomic layer deposition (ALD) reactor;
• providing a high-aspect ratio substrate;
• providing a first non-halogenated precursor comprising Bis(N,N′-di-sec-butylacetamidinato)dicopper(I);
• providing a second non-halogenated precursor comprising a sulfur compound;
• reacting the first non-halogenated precursor in the ALD reactor for a first period;
• reacting the second non-halogenated precursor in the ALD reactor for a second period;
• and
• repeating the reactions of the first non-halogenated precursor and the second non-halogenated precursor for a number of cycles until a chalcocite film of a desired thickness is formed on the high-aspect ratio substrate;
• wherein an average growth rate of the chalcocite film of at least about 0.9 Å per cycle is achieved.