In one implementation, a trench field-effect transistor (trench FET) includes a semiconductor substrate having a drain region, a drift zone over the drain region, and depletion trenches formed over the drain region. Each depletion trench includes a depletion trench dielectric and a depletion electrode. The trench FET can further include a respective bordering gate trench situated alongside each depletion trench, each bordering gate trench having a gate electrode and a gate dielectric. The gate dielectric is merged with the depletion trench dielectric between the depletion electrode and the gate electrode.