Semiconductor device
View Patent ↗A unipolar semiconductor device having a drift layer ( 3 ) doped according to a first conductivity type forming a conducting path and regions ( 7, 8 ) doped according to a second conductivity type and arranged next to the drift layer, has the drift layer and the regions of a semiconductor material having an ionization energy Ei of dopants of the second conductivity type therein exceeding 0.5 eV and/or a solubility of the dopants of the second conductivity type therein being less than 10 18 cm −3 .
1. A semiconductor device having a source contact ( 1 ) and a drain contact ( 2 ) interconnected by a drift layer ( 3 ) doped by dopants according to a first conductivity type, n or p, for majority charge carrier transport in a conducting path ( 13 ) between the source contact and the drain contact in a forward biased state of the device, said device also comprising regions ( 7 , 8 , 15 - 17 ) doped by dopants according to a second conductivity type being opposite to said first type, said regions being arranged next to the drift layer so as to deplete parts thereof and being able to form a blocking pn-junction in said conducting path between the source contact and the drain contact for preventing a current to flow between the source contact and the drain contact in a blocking state of the device, wherein said drift layer and said regions are of a semiconductor material having an ionisation energy Ei of said dopants of said second conductivity type in this semiconductor material exceeding 0.5 eV and/or a solubility of said dopants of said second conductivity type in this semiconductor material being less than 10 18 cm −3 .
2. A device according to claim 1 , wherein said semiconductor material is a material having an energy gap between the valence band and the conduction band exceeding 2 eV.
3. A device according to claim 1 , wherein said semiconductor material is diamond.
4. A device according to claim 3 , wherein said first conductivity type is p and said second conductivity type is n.
5. A device according to claim 4 , wherein said dopants of said first conductivity type is B.
6. A device according to claim 4 , wherein said dopants of said second conductivity type is N.
7. A device according to claim 1 , wherein said semiconductor material is AlN, BN or ZnO.
8. A device according to claim 7 , wherein said dopants of said second conductivity type have an ionisation energy Ei in said semiconductor material exceeding 0.5 eV.
9. A device according to claim 7 , wherein said semiconductor material is AlN and said first conductivity type is n.
10. A device according to claim 1 , wherein it is a Junction Barrier Shottky-device (JBS) and said regions ( 15 - 17 ) are adapted to form a grid ( 14 ) and are laterally separated by portions ( 20 , 21 ) of said drift layer, and said grid is adapted to form said blocking pn-junction ( 23 ) in said blocking state of the device by completely depleting said portions of the drift layer, so that a continuous layer doped according to said second conductivity type is formed by said grid and said portions.
11. A device according to claim 10 , wherein said semiconductor material is diamond and said source contact ( 1 ) forming a contact to said portions of the drift layer and a Shottky-barrier thereto is made of Al, Pt or Ti.
12. A device according to claim 1 , wherein it is a Junction Field Effect Transistor (JFET) with said regions ( 7 , 8 ) forming a gate and connectable to a voltage source ( 9 , 10 ) for controlling the depletion of said conducting path ( 13 ) of the drift layer ( 3 ).
13. A device according to claim 1 , wherein said drift layer ( 3 ) also comprises a first sub-layer ( 5 ) having a higher doping concentration than the rest of the drift layer and located next to the drain contact ( 2 ), and that said regions ( 7 , 8 , 15 - 17 ) are located close to said source contact ( 1 ).
14. A device according to claim 1 , wherein said drift layer ( 3 ) has a sub-layer ( 22 ) with a lower doping concentration than the rest of the drift layer and located next to said regions ( 15 , 16 ) for facilitating depletion of the drift layer next to these regions.
15. A device according to claim 14 , wherein said sub-layer ( 22 ) of the drift layer is located close to said source contact ( 1 ).
16. A device according to claim 2 , wherein said semiconductor material is diamond.
17. A device according to claim 16 , wherein said first conductivity type is p and said second conductivity type is n.
18. A device according to claim 17 , wherein said dopants of said first conductivity type is B.
19. A device according to claim 18 , wherein said dopants of said second conductivity type is N.
20. A device according to claim 5 , wherein said dopants of said second conductivity type is N.