An electronic device can include a substrate, an active region of a transistor, and a shield electrode. The substrate can define a trench and include a mesa adjacent to the trench, and the shield electrode can be within the trench. In an embodiment, the electronic device can further include an active region of a transistor within the mesa and an insulating layer including a thicker section and a thinner section closer to a bottom of the trench. In another embodiment, the electronic device can include a body region and a doped region within the mesa and spaced apart from the body region by a semiconductor region. The doped region can have a dopant concentration that is higher than a dopant concentration of the semiconductor region and a portion of the substrate underlying the doped region.