Space charge trap-assisted recombination suppressing layer for low-voltage diode operation
View Patent ↗Shockley-Read-Hall (SRH) generation and/or recombination in heterojunction devices is suppressed by unconventional doping at or near the heterointerface. The effect of this doping is to shift SRH generation and/or recombination preferentially into the wider band gap material of the heterojunction. This reduces total SRH generation and/or recombination in the device by decreasing the intrinsic carrier concentration n i at locations where most of the SRH generation and/or recombination occurs. The physical basis for this effect is that the SRH generation and/or recombination rate tends to decrease as n i around the depletion region decreases, so decreasing the effective n i in this manner is a way to decrease SRH recombination.
1. Apparatus comprising:
a first semiconductor material;
a second semiconductor material having a larger band gap than the first semiconductor material;
wherein a heterojunction is formed at a composition interface between the first semiconductor material and the second semiconductor material;
wherein dopant impurities are present at or near the composition interface to create a p-n junction having a doping interface;
wherein a doping profile of the dopant impurities at or near the composition interface is configured to preferentially shift Shockley-Read-Hall (SRH) generation and/or recombination into the second semiconductor material.
2. A light emitting diode including the apparatus of claim 1 , wherein a band gap of the first semiconductor material is in a range from 0.7 eV to 5 eV.
3. A solar photovoltaic device including the apparatus of claim 1 , wherein a band gap of the first semiconductor material is in a range from 1.1 eV to 1.9 eV.
4. A thermo-photovoltaic device including the apparatus of claim 1 , wherein a band gap of the first semiconductor material is in a range from 0.5 eV to 1.45 eV.
5. A photodetector including the apparatus of claim 1 , wherein a band gap of the first semiconductor material is in a range from 0.5 eV to 1.2 eV.
6. The apparatus of claim 1 , wherein V gap is a voltage corresponding to an energy band gap of the first semiconductor material, wherein V thermal is a thermal voltage, and wherein the apparatus is included in a diode configured to be operated in a forward bias voltage range from V gap /2 to V gap −3V thermal .
7. The apparatus of claim 1 , wherein the heterojunction is a type I heterojunction.
8. The apparatus of claim 1 , wherein the heterojunction is a type II heterojunction.
9. The apparatus of claim 1 , wherein a conduction band discontinuity of the heterojunction is less than a valence band discontinuity of the heterojunction, wherein the second material is doped n-type and wherein the first material is doped p-type.
10. The apparatus of claim 1 , wherein a conduction band discontinuity of the heterojunction is greater than a valence band discontinuity of the heterojunction, wherein the second material is doped p-type and wherein the first material is doped n-type.
11. The apparatus of claim 1 , wherein the doping profile includes a first region of the first material at or near the composition interface and having a larger doping concentration than an adjacent part of the first material.
12. The apparatus of claim 11 , wherein a thickness of the first region is 50 nm or less.
13. The apparatus of claim 1 , wherein the doping profile includes a second region of the second material at or near the composition interface and having a smaller doping concentration than an adjacent part of the second material.
14. The apparatus of claim 13 , wherein a thickness of the second region is 200 nm or less.
15. The apparatus of claim 1 , wherein the doping interface coincides with the composition interface.
16. The apparatus of claim 1 , wherein the doping interface is separated from the composition interface by 100 nm or less.
17. The apparatus of claim 1 , wherein the doping profile is graded at a location of the doping interface.