Structures with boron- and gallium-doped silicon germanium layers and methods and systems for forming same

A method of forming a doped silicon germanium layer, the method comprising:

• generating a heteroleptic gallium precursor using a first gallium precursor and a second gallium precursor, the first gallium precursor comprising at least one straight chain alkyl group, the second gallium precursor comprising at least one tertiary alkyl group, and the heteroleptic gallium precursor comprising (i) the at least one straight chain alkyl group in which a terminal carbon is directly bonded to gallium, and (ii) the at least one tertiary alkyl group in rich a tertiary carbon is directly bonded to the gallium, wherein the generating includes moving the at least one straight chain alkyl group from the first gallium precursor to the second gallium precursor or moving the at least one tertiary allyl group from the second gallium precursor to the first gallium precursor;
• simultaneously exposing a substrate to (a) a silicon precursor, (b), a germanium precursor, (c) a boron precursor, and (d) the heteroleptic gallium precursor;
• and
• reacting the silicon precursor, the germanium precursor, the boron precursor, and the heteroleptic gallium precursor to form, on the substrate, a silicon germanium layer that is doped with boron and gallium.