Semiconductor device structures with self-aligned doped regions and methods for forming such semiconductor device structures. The semiconductor structure comprises first and second doped regions of a first conductivity type defined in the semiconductor material of a substrate bordering a sidewall of a trench. An intervening region of the semiconductor material separates the first and second doped regions. A third doped region is defined in the semiconductor material bordering the sidewall of the trench and disposed between the first and second doped regions. The third doped region is doped to have a second conductivity type opposite to the first conductivity type. Methods for forming the doped regions involve depositing either a layer of a material doped with both dopants or different layers each doped with one of the dopants in the trench and, then, diffusing the dopants from the layer or layers into the semiconductor material bordering the trench sidewall.