Some examples herein provide a method of forming a doped silicon germanium layer. The method may include simultaneously exposing a substrate to (a) a silicon precursor, (b), a germanium precursor, (c) a boron precursor, and (d) a heteroleptic gallium precursor. The heteroleptic gallium precursor may include (i) at least one straight chain alkyl group in which a terminal carbon is directly bonded to gallium, and (ii) at least one tertiary alkyl group in which a tertiary carbon is directly bonded to gallium. The method may include reacting the silicon precursor, the germanium precursor, the boron precursor, and the heteroleptic gallium precursor to form a silicon germanium layer on the substrate that is doped with boron and gallium.

Some examples herein provide a method of forming a doped silicon germanium layer. The method may include simultaneously exposing a substrate to (a) a silicon precursor, (b), a germanium precursor, (c) a boron precursor, and (d) a heteroleptic gallium precursor. The heteroleptic gallium precursor may include (i) at least one straight chain alkyl group in which a terminal carbon is directly bonded to gallium, and (ii) at least one tertiary alkyl group in which a tertiary carbon is directly bonded to gallium. The method may include reacting the silicon precursor, the germanium precursor, the boron precursor, and the heteroleptic gallium precursor to form a silicon germanium layer on the substrate that is doped with boron and gallium.

Methods for selectively depositing a boron doped silicon germanium layer on a substrate disposed within a reaction chamber are disclosed. The methods disclosed include selectively depositing the boron doped silicon germanium layers by an epitaxial deposition process employing a silicon precursor, a germanium halide precursor, and a boron halide dopant precursor.