A monolithic semiconductor structure includes a stack of layers. The stack includes a substrate; a first layer made from a first semiconductor material; and a second layer made from a second semiconductor material. The first layer is situated between the substrate and the second layer and at least one of the first semiconductor material and the second semiconductor material contains a III-nitride material. The structure includes a power transistor, including a body formed in the stack of layers; a first power terminal at a side of the first layer facing the second layer; a second power terminal at least partly formed in the substrate; and a gate structure for controlling the propagation through the body of electric signals between the first power terminal and the second power terminal. The structure further includes a vertical Schottky diode, including: an anode; a cathode including the substrate, and a Schottky barrier between the cathode and the anode, the Schottky barrier being situated between the substrate and a anode layer in the stack of layers.