Semiconductor device and method for driving the same

A semiconductor device, comprising:

• a semiconductor layer stack of a nitride semiconductor or a silicon carbide semiconductor formed on a substrate and having a channel region;
• a first electrode and a second electrode formed spaced apart from each other on the semiconductor layer stack;
• and
• a first gate electrode formed between the first electrode and the second electrode, and a second gate electrode formed between the first gate electrode and the second electrode, wherein:
• a potential greater than the threshold voltage of the first gate electrode with reference to the potential of the first electrode is applied to the first gate electrode and a potential greater than the threshold voltage of the second gate electrode with reference to the potential of the second electrode is applied to the second gate electrode, whereby the semiconductor device is brought to a conductive state in which a current flows in both directions between the first electrode and the second electrode;
• and
• a potential less than or equal to the threshold voltage of the first gate electrode with reference to the potential of the first electrode is applied to the first gate electrode and a potential less than or equal to the threshold voltage of the second gate electrode with reference to the potential of the second electrode is applied to the second gate electrode, whereby the semiconductor device is brought to a non-conductive state in which a current does not flow in either direction between the first electrode and the second electrode.

A semiconductor device, comprising:

• a substrate;
• a semiconductor layer stack of a nitride semiconductor or a silicon carbide semiconductor formed on a disposed above the substrate and, the semiconductor layer stack having a channel region;
• a first electrode and a second electrode formed disposed spaced apart from each other on the semiconductor layer stack;
• a first gate electrode disposed between the first electrode and the second electrode;
• a first control layer having a p-type conductivity formed disposed between the semiconductor layer stack and the first gate electrode;
• and
• a third control second layer having a p-type conductivity formed disposed between the semiconductor layer stack and the second electrode.

A bidirectional switch, comprising:

• a semiconductor layer stack of a nitride semiconductor or a silicon carbide semiconductor formed on a substrate and having a channel region;
• a first electrode and a second electrode formed spaced apart from each other on the semiconductor layer stack;
• a first gate electrode formed between the first electrode and the second electrode, and a second gate electrode formed between the first gate electrode and the second electrode;
• and
• a control section for controlling a voltage applied to the first gate electrode and second gate electrode, wherein:
• in a conductive state in which a current flows in both directions between the first electrode and the second electrode, the control section applies, to the first gate electrode, a voltage higher than a threshold voltage of the first gate electrode with reference to a potential of the first electrode, and applies, to the second gate electrode, a voltage higher than a threshold voltage of the second gate electrode with reference to a potential of the second electrode;
• and
• in a non-conductive state in which a current does not flow in either direction between the first electrode and the second electrode, the control section applies, to the first gate electrode, a voltage less than or equal to the threshold voltage of the first gate electrode with reference to the potential of the first electrode, and applies, to the second gate electrode, a voltage less than or equal to the threshold voltage of the second gate electrode with reference to the potential of the second electrode.

A method for driving a semiconductor device including a semiconductor element, the semiconductor element including a first electrode, a first gate electrode, a second gate electrode and a second electrode formed in this order while being spaced apart from one another on a semiconductor layer stack, which is formed on a substrate, the method comprising the steps of:

• a step of applying a potential greater than a threshold voltage of the first gate electrode with reference to a potential of the first electrode to the first gate electrode and applying a potential less than or equal to a threshold voltage of the second gate electrode with reference to a potential of the second electrode to the second gate electrode, whereby the semiconductor device is brought to a reverse-blocking state in which a current flows from the second electrode to the first electrode but not from the first electrode to the second electrode;
• and
• a step of applying a potential less than or equal to the threshold voltage of the first gate electrode with reference to the potential of the first electrode to the first gate electrode and applying a potential less than or equal to the threshold voltage of the second gate electrode with reference to the potential of the second electrode to the second gate electrode, whereby the semiconductor device is brought to a non-conductive state in which a current does not flow in either direction between the first electrode and the second electrode.

A method for driving a semiconductor device including a semiconductor element, the semiconductor element including a first electrode, a first gate electrode, a second gate electrode and a second electrode formed in this order while being spaced apart from one another on a semiconductor layer stack, which is formed on a substrate, the method comprising the steps of:

• a step of applying a potential greater than the threshold voltage of the first gate electrode with reference to the potential of the first electrode to the first gate electrode and applying a potential greater than the threshold voltage of the second gate electrode with reference to the potential of the second electrode to the second gate electrode, whereby the semiconductor device is brought to a conductive state in which a current flows in both directions between the first electrode and the second electrode;
• and
• a step of applying a potential less than or equal to the threshold voltage of the first gate electrode with reference to the potential of the first electrode to the first gate electrode and applying a potential less than or equal to the threshold voltage of the second gate electrode with reference to the potential of the second electrode to the second gate electrode, whereby the semiconductor device is brought to a non-conductive state in which a current does not flow in either direction between the first electrode and the second electrode.

A semiconductor device comprising:

• a substrate;
• a semiconductor layer stack of a nitride semiconductor or a silicon carbide semiconductor disposed above the substrate, the semiconductor layer stack having a channel region;
• a first electrode disposed on the semiconductor layer stack;
• a second electrode disposed on the semiconductor layer stack;
• a first layer having a p-type conductivity, the first layer disposed on the semiconductor layer stack and disposed between the first electrode and the second electrode;
• a second layer having a p-type conductivity, the second layer disposed on the semiconductor layer stack and disposed between the first layer and the second electrode;
• a third electrode disposed on the first layer;
• and
• a fourth electrode disposed on the second layer, wherein:
• the semiconductor layer stack includes a first region having a first thickness and a second region having a second thickness, the first thickness being greater than the second thickness,
• the first layer and the second layer are disposed on the first region, and
• at least a portion of the second region is disposed between the first layer and the second layer.

A semiconductor device comprising:

• a substrate;
• a semiconductor layer stack of a nitride semiconductor or a silicon carbide semiconductor disposed above the substrate, the semiconductor layer stack having a channel region;
• a first electrode disposed on the semiconductor layer stack;
• a second electrode disposed on the semiconductor layer stack;
• a third electrode disposed on the semiconductor layer stack and disposed between the first electrode and the second electrode;
• and
• a fourth electrode disposed on the semiconductor layer stack and disposed between the third electrode and the second electrode,
• wherein the fourth electrode is electrically connected to the second electrode.

A semiconductor device comprising:

• a substrate;
• a semiconductor layer stack of a nitride semiconductor or a silicon carbide semiconductor disposed above the substrate, the semiconductor layer stack having a channel region;
• a first electrode disposed on the semiconductor layer stack;
• a second electrode disposed on the semiconductor layer stack;
• a third electrode disposed on the semiconductor layer stack and disposed between the first electrode and the second electrode;
• a layer having a p-type conductivity, the layer disposed on the semiconductor layer stack and disposed between the third electrode and the second electrode;
• and
• a fourth electrode disposed on the layer, wherein:
• the layer forms a pn junction with the semiconductor layer stack, and
• a voltage higher than a built-in voltage of the pn junction is applied to the fourth electrode.

A semiconductor device, comprising:

• a substrate;
• a semiconductor layer stack of a nitride semiconductor or a silicon carbide semiconductor disposed above the substrate, the semiconductor layer stack having a channel region;
• a first electrode and a second electrode disposed spaced apart from each other on the semiconductor layer stack;
• a first gate electrode disposed on the semiconductor layer stack and disposed between the first electrode and the second electrode;
• and
• a layer having a p-type conductivity and disposed between the semiconductor layer stack and the second electrode.