A bipolar junction transistor a base over a collector, the base including a III-V ternary semiconductor alloy including first, second, and third elements. The LI-V ternary semiconductor alloy has a narrower bandgap than a binary semiconductor alloy including only the first and second elements. A ledge between an emitter and a base contact being 0.5 m or less.

A bipolar junction transistor has a collector over a substrate and a base structure over the collector, the base including a III-V ternary semiconductor alloy, the base having a base contact formed thereon. An emitter is over the base structure, and a ledge between the emitter structure and the base contact is 0.3 m or less.

A bipolar junction transistor has a collector over a substrate and a multi-layer base structure over the collector, and an emitter over the base structure. The multi-layer base structure includes a first layer having a first III-V semiconductor alloy and a second layer having a second III-V semiconductor alloy having a different composition of elements than the first III-V semiconductor alloy. The second layer has a narrower bandgap than the first layer. The first layer is positioned between the collector and the second layer.

Provided is a method for manufacturing a semiconductor device that improves the reliability of the semiconductor device. An opening is formed in an insulating film formed over a semiconductor substrate. At that time, a mask layer for formation of the opening is formed over the insulating film. The insulating film is dry etched and then wet etched. The dry etching step is finished before the semiconductor substrate is exposed at the bottom of the opening, and the wet etching step is finished after the semiconductor substrate is exposed at the bottom of the opening.

In a general aspect, a power semiconductor device can include a collector region disposed on a substrate, the collector region can include n-type silicon carbide (SiC). The power semiconductor device can also include a base region disposed on the collector region. The base region can include p-type SiC doped with gallium. The power semiconductor device can include an emitter region disposed on the base region. The emitter region can include n-type SiC carbide.

A bipolar junction transistor includes an emitter, a base contact, a collector and a shallow trench isolation. The base contact has two base fingers that form a corner to receive the emitter. The collector has two collector fingers extending along the base fingers of the base contact. The shallow trench isolation is disposed in between the emitter and the base contact and in between the base contact and the collector.

A symmetrically-bidirectional bipolar transistor circuit where the two base contact regions are clamped, through a low-voltage diode and a resistive element, to avoid bringing either emitter junction to forward bias. This avoids bipolar gain in the off state, and thereby avoids reduction of the withstand voltage due to bipolar gain.

Device structures and fabrication methods for a bipolar junction transistor. A first semiconductor layer is formed on a substrate containing a first terminal. An etch stop layer is formed on the first semiconductor layer, and a second semiconductor layer is formed on the etch stop layer. The second semiconductor layer is etched to define a second terminal at a location of an etch mask on the second semiconductor layer. A first material comprising the etch stop layer and a second material comprising the second semiconductor layer are selected such that the second material of the second semiconductor layer etches at a greater etch rate than the first material of the etch stop layer. The first semiconductor layer may be a base layer that is used to form an intrinsic base and an extrinsic base of the bipolar junction transistor.

A two-transistor memory cell based upon a thyristor for an SRAM integrated circuit is described together with a process for fabricating it. The memory cell can be implemented in different combinations of MOS and bipolar select transistors, or without select transistors, with thyristors in a semiconductor substrate with shallow trench isolation. Standard CMOS process technology can be used to manufacture the SRAM.

A three terminal high voltage Darlington bipolar transistor power switching device includes two high voltage bipolar transistors, with collectors connected together serving as the collector terminal. The base of the first high voltage bipolar transistor serves as the base terminal. The emitter of the first high voltage bipolar transistor connects to the base of the second high voltage bipolar transistor (inner base), and the emitter of the second high voltage bipolar transistor serves as the emitter terminal. A diode has its anode connected to the inner base (emitter of the first high voltage bipolar transistor, or base of the second high voltage bipolar transistor), and its cathode connected to the base terminal. Similarly, a three terminal hybrid MOSFET/bipolar high voltage switching device can be formed by replacing the first high voltage bipolar transistor of the previous switching device by a high voltage MOSFET.