Semiconductor device

A semiconductor device, comprising:

• a substrate;
• a first transistor of a depletion type, the first transistor being provided on the substrate and including a channel region of a first conductivity type, the channel region of the first transistor including a nitride semiconductor;
• a second transistor of an enhancement type, the second transistor being provided on the substrate, the first and second transistors being connected in series, the second transistor including another channel region of the first conductivity type and operating via an inversion layer of a second conductivity type induced in said another channel region, the second conductivity type being an opposite polarity of the first conductivity type;
• a gate control circuit connected to a gate electrode of the second transistor;
• and
• a sealing member sealing the first transistor, the second transistor, and the gate control circuit on the substrate,
• the substrate including a gate terminal and a power supply terminal, the gate terminal being electrically connected to a gate electrode of the first transistor, the power supply terminal being electrically connected to a connection part between the first transistor and the second transistor, the power supply terminal supplying a power supply voltage to the gate control circuit.