Systems, circuits, devices, and methods with bidirectional bipolar transistors
Methods, systems, circuits, and devices for power-packet-switching power converters using bidirectional bipolar transistors (BTRANs) for switching. Four-terminal three-layer BTRANs provide substantially identical operation in either direction with forward voltages of less than a diode drop. BTRANs are fully symmetric merged double-base bidirectional bipolar opposite-faced devices which operate under conditions of high non-equilibrium carrier concentration, and which can have surprising synergies when used as bidirectional switches for power-packet-switching power converters. BTRANs are driven into a state of high carrier concentration, making the on-state voltage drop very low.
1. A bidirectional power switching apparatus, comprising:
first and second first-conductivity-type emitter regions on opposing faces of a second-conductivity-type semiconductor mass, and
first and second second-conductivity-type base contact regions, in proximity to said first and second emitter regions respectively; and
a drive circuit which, when the control circuitry selects one of said bidirectional switches for turn-on, drives the first and second base contact regions of that switch differently, to forward bias the associated emitter-base junction and permit majority carriers to flow to the associated emitter regions from the emitter regions on the opposing surface;
wherein the drive circuit applies sufficient current to the selected base contact region to generate a nonequilibrium carrier concentration, in the interior of said semiconductor mass, which is more than thirty times as great as the off-state equilibrium majority carrier concentration, to thereby lower the voltage drop across the second-conductivity-type semiconductor mass.
2. The bidirectional power switching apparatus of claim 1 , wherein, when emitter regions on one face are acting as emitters, the emitter regions on the opposing face act as collectors.
3. The bidirectional power switching apparatus of claim 1 , wherein the second-conductivity-type base contact regions are more highly doped than the second-conductivity-type semiconductor mass.
4. The bidirectional power switching apparatus of claim 1 , further comprising a thin layer of tunnel oxide between said first-conductivity-type emitter regions and said second-conductivity-type semiconductor mass.
5. The bidirectional power switching apparatus of claim 1 , further comprising a thin layer of tunnel oxide between said first-conductivity-type emitter regions and respective emitter metallizations.
6. The bidirectional power switching apparatus of claim 1 , wherein emitter-base junctions are heterojunction.
7. The bidirectional power switching apparatus of claim 1 , wherein the first-conductivity-type emitter regions are amorphous silicon, and the second-conductivity-type semiconductor mass is substantially monocrystalline silicon.
8. The bidirectional power switching apparatus of claim 1 , wherein the first-conductivity-type emitter regions are polycrystalline silicon, and the second-conductivity-type semiconductor mass is substantially monocrystalline silicon.
9. A bidirectional power switching apparatus, comprising:
first and second first-conductivity-type emitter regions on opposing faces of a second-conductivity-type semiconductor mass, and
first and second second-conductivity-type base contact regions, in proximity to said first and second emitter regions respectively; and
a drive circuit which, when the control circuitry selects one of said bidirectional switches for turn-on, drives a base contact region of that switch, to forward bias the associated emitter-base junction and permit majority carriers to flow to the emitter regions on the opposing surface;
wherein the drive circuit applies sufficient current to the selected base contact region to generate a nonequilibrium carrier concentration, in the interior of said semiconductor mass, which is more than thirty times as great as the off-state equilibrium majority carrier concentration, to thereby lower the voltage drop across the second-conductivity-type semiconductor mass; and
further comprising oxide-filled trenches between each said first-conductivity-type emitter region and respectively adjacent second-conductivity-type base contact regions.
10. A bidirectional power switching apparatus, comprising:
first and second first-conductivity-type emitter regions on opposing faces of a second-conductivity-type semiconductor mass, and
first and second second-conductivity-type base contact regions, in proximity to said first and second emitter regions respectively; and
a drive circuit which, when the control circuitry selects one of said bidirectional switches for turn-on, drives the first and second base contact regions of that switch differently, to thereby permit current to flow in a predetermined direction between said first and second emitter regions on the opposing faces of said respective semiconductor mass;
wherein the drive circuit applies sufficient current to the selected base contact region to generate a nonequilibrium carrier concentration, in the interior of said semiconductor mass, which is more than thirty times as great as the off-state equilibrium majority carrier concentration, to thereby lower the voltage drop across the second-conductivity-type semiconductor mass; and
further comprising an edge termination structure which comprises a first-conductivity-type region in a second-conductivity-type region.