forming an opening through a multilayer stack and into a substrate;

depositing a barrier layer at a bottom of the opening, wherein after the depositing the barrier layer a top level of the barrier layer is below a bottom of the multilayer stack, wherein the barrier layer is meniscus shaped, wherein the depositing the barrier layer comprises performing a bottom-up deposition of an undoped silicon material, and wherein the bottom-up deposition is performed until the barrier layer has a first thickness adjacent to a bottom of the opening and a second thickness different from the first thickness, the second thickness being adjacent to a sidewall of the substrate, and wherein a ratio of the second thickness to the first thickness is between about 1:1 and about 1:10;

forming a multilayer source/drain region over the barrier layer by depositing a first semiconductor material over the barrier layer; and

forming a stack of nanostructures by removing sacrificial layers of the multilayer stack, the multilayer source/drain region being electrically coupled to the stack of nanostructures.