Structures for a field-effect transistor and methods of forming a structure for a field-effect transistor. A gate structure extends over a semiconductor body, a first source/drain region includes an epitaxial semiconductor layer on a first portion of the semiconductor body, and a second source/drain region is positioned in a second portion of the semiconductor body. The gate structure includes a first sidewall and a second sidewall opposite the first sidewall, the first source/drain region is positioned adjacent to the first sidewall of the gate structure, and the second source/drain region is positioned adjacent to the second sidewall of the gate structure. The first source/drain region has a first width, and the second source/drain region has a second width that is greater than the first width.