Voltage-matched, monolithic, multi-band-gap devices
View Patent ↗Monolithic, tandem, photonic cells include at least a first semiconductor layer and a second semiconductor layer, wherein each semiconductor layer includes an n-type region, a p-type region, and a given band-gap energy. Formed within each semiconductor layer is a sting of electrically connected photonic sub-cells. By carefully selecting the numbers of photonic sub-cells in the first and second layer photonic sub-cell string(s), and by carefully selecting the manner in which the sub-cells in a first and second layer photonic sub-cell string(s) are electrically connected, each of the first and second layer sub-cell strings may be made to achieve one or more substantially identical electrical characteristics.
1. A two-terminal, monolithic, tandem photonic device comprising:
a first layer of semiconductor material having an n-type region, a p-type region, and a first band-gap energy;
a plurality of first layer sub-cells formed in the first layer and electrically connected in series to form a two-terminal first layer sub-cell string;
a second layer of semiconductor material having an n-type region, a p-type region, and a second band-gap energy; and
a plurality of second layer sub-cells formed in the second layer and electrically connected in series to form a two-terminal second layer sub-cell, wherein the first layer sub-cell string and the second layer sub-cell string are electrically connected in parallel to form the two-terminal, monolithic, tandem photonic device.
2. A two-terminal, monolithic, tandem photonic device as defined in claim 1 , wherein each sub-cell in the first layer of semiconductor material has substantially the same outer circumferential shape.
3. A two-terminal, monolithic, tandem photonic device as defined in claim 2 , wherein each sub-cell in the second layer of semiconductor material has substantially the same outer circumferential shape.
4. A two-terminal, monolithic, tandem photonic device as defined in claim 3 , wherein the outer circumferential shapes of the first layer sub-cells and the second layer sub-cells are substantially the same shape.
5. A two-terminal, monolithic, tandem photonic device as defined in claim 1 , wherein the first layer of semiconductor material and the second layer of semiconductor material are formed epitaxially on a substrate.
6. A two-terminal, monolithic, tandem photonic device as defined in claim 1 , wherein the substrate is formed monolithically with the first layer of semiconductor material and the second layer of semiconductor material.
7. A two-terminal, monolithic, tandem photonic device as defined in claim 3 , wherein the number of first layer sub-cells is not equal to the number of second layer sub-cells.
8. A two-terminal, monolithic, tandem photonic device as defined in claim 3 , further comprising a third layer of semiconductor material heaving an n-type region, a p-type region, a third band-gap energy, and a plurality of third layer sub-cells formed in the third layer and electrically connected in series to form a two-terminal third layer sub-cell, wherein the number of third layer sub-cells is the same as the number of first layer sub-cells and wherein the first layer sub-cell string and the second layer sub-cell string are electrically connected in parallel to form the two-terminal, monolithic, tandem photonic device.
9. A two-terminal, monolithic, tandem photonic device as defined in claim 1 wherein the photonic device comprises a photovoltaic (PV) cell.
10. A PV cell as defined in claim 9 , wherein the first band-gab energy and second band-gab energy are not equivalent in value.
11. A two-terminal, monolithic, tandem photonic device as defined in claim 1 , wherein the photonic device comprises a light emitting diode (LED) cell.
12. A LED cell as defined in claim 1 , wherein the first band-gab energy and the second band-gab energy are not equivalent in value.
13. A monolithic, tandem photonic device comprising:
a first layer of semiconductor material having an in-type region, a p-type region, a first band-gap energy, and a plurality of sub-cells formed therein;
a second layer of semiconductor material having an n-type region, a p-type region, a second band-gap energy, and a plurality sub-cells formed therein; and
a plurality of sub-cell strings, each of the plurality of sub-cell strings comprising two or more electrically interconnected sub-cells; wherein the plurality of sub-cell strings are electrically connected to one another in parallel.
14. A monolithic, tandem photonic device as defined in claim 13 , wherein the plurality of sub-cell strings comprises at least one first layer sub-cell string including only sub-cell sub-cells formed in the first layer and at least one second layer sub-cell string including only sub-cells formed in the second layers.
15. A monolithic, tandem photonic device as defined in claim 14 , wherein each of the sub-cells in the at least one first layer sub-cell string are electrically connected in series.
16. A monolithic, tandem photonic device as defined in claim 15 , wherein each of the sub-cells in the at least one second layer sub-cell string are electrically connected in a combination of series and parallel connections.
17. A monolithic, tandem photonic device as defined in claim 14 , wherein each of the sub-cells in the at least one second layer sub-cell string are electrically connected in series.
18. A monolithic, tandem photonic device as defined in claim 17 , wherein the photonic device includes a plurality of first layer sub-cell strings and a plurality of second layer sub-cell strings, wherein each of the sub-cell strings in the plurality of first layer sub-cell strings are physically arranged along substantially linear axes that are substantially parallel with one another, and wherein each sub-cell strings in the plurality of second layer sub-cell strings are arranged along substantially linear axes that are substantially parallel with one another.
19. A monolithic, tandem photonic device as defined in claim 18 , wherein the plurality of first layer sub-cell strings and the plurality of second layer sub-cell strings are substantially perpendicular to one another.
20. A monolithic, tandem photonic device as defined in claim 13 , wherein the first layer sub-cell string includes a plurality of sub-cell sub-strings, each sub-cell sub-string including at least two serially connected sub-cells.
21. A monolithic, tandem photonic device as defined in claim 20 , wherein each of the sub-cell sub-strings are electrically connected in parallel.
22. A monolithic, tandem photonic device as defined in claim 20 , further comprising a negative bus bar and a positive bus bar, wherein each sub-cell sub-string includes a negative terminal and a positive terminal, and wherein the negative terminal of each sub-cell sub-string is connected to the negative bus bar and the positive terminal of each sub-cell sub-string is connected to the positive bus bar.
23. A monolithic, tandem photonic device as defined in claim 21 , wherein the second layer sub-cell string includes a plurality of sub-cell sub-strings, each sub-cell sub-string including at least two serially connected sub-cells.
24. A monolithic, tandem photonic device as defined in claim 23 , further comprising a negative bus bar and a positive bus bar, wherein each sub-cell sub-string includes a negative terminal and a positive terminal, and wherein the negative terminal of each sub-cell sub-string is connected to the negative bus bar and the positive terminal of each sub-cell sub-string is connected to the positive bus bar.
25. A two-terminal, monolithic, tandem photonic device as defined in claim 13 , wherein the photonic device comprises a photovoltaic (PV) cell.
26. A PV cell as defined in claim 25 , wherein the values of the first band-gab energy, second band-gab energy, and third band-gab energy are not equivalent.
27. A two-terminal, monolithic, tandem photonic device as defined in claim 13 , wherein the photonic device comprises a photovoltaic (PV) cell.
28. A PV cell as defined in claim 27 , wherein the first band-gab energy and second band-gab energy are not equivalent in value.
29. A two-terminal, monolithic, tandem photonic device as defined in claim 13 , wherein the photonic device comprises a light emitting diode (LED) cell.
30. A LED cell as defined in claim 29 , wherein the first band-gab energy and the second hand-gab energy are not equivalent in value.
31. A two-terminal, monolithic, tandem light emitting diode (LED) device comprising:
a first layer of semiconductor material having an n-type region, a p-type region, and a first band-gap energy;
a plurality of first layer LED sub-cells formed in the first layer and electrically connected to form a two-terminal first layer sub-cell string;
a second layer of semiconductor material having an n-type region, a p-type region, and a second band-gap energy; and
a plurality of second layer LED sub-cells formed in the second layer and electrically connected to form a two-terminal second layer sub-cell, wherein the first layer sub-cell string and the second layer sub-cell string are separately electrically biased, and wherein the first band-gap energy and the second band gap-energy are not equivalent in value.
32. A monolithic, tandem LED device as defined in claim 31 , wherein each LED sub-cell in the LED device has substantially the same outer circumferential shape.
33. A monolithic, tandem LED device as defined in claim 31 , wherein each of the LED sub-cells in the first layer sub-cell string are electrically connected in series and biased at a first voltage.
34. A monolithic, tandem LED device as defined in claim 33 , wherein each of the LED sub-cells in the second layer sub-cell string are electrically connected in series and biased at a second voltage.
35. A monolithic, tandem LED device as defined in claim 34 , wherein the first voltage and the second voltage are not equivalent.
36. A monolithic, tandem LED device as defined in claim 35 wherein each of the LED sub-cells in the first layer LED sub-cell string are arranged along a substantially linear first layer axis.
37. A monolithic, tandem LED device as defined in claim 36 , wherein each of the LED sub-cells in the second layer LED sub-cell string are arranged along a substantially linear, second layer axis.
38. A monolithic, tandem LED device as defined in claim 37 , wherein the first layer axis and the second layer axis are substantially perpendicular with one another.
39. A monolithic, tandem LED device as defined in claim 37 , wherein the first layer axis and the second layer axis are substantially parallel with one another.
40. A monolithic, tandem LED device as defined in claim 33 , wherein each of the LED sub-cells in the second layer sub-cell string are electrically connected in a combination of series and parallel connections and biased at a second voltage.
41. A two-terminal, monolithic, tandem photonic device comprising:
a first layer of semiconductor material having an n-type region, a p-type region, and a first band-gap energy;
a plurality of first layer sub-cells formed in the first layer along a first axis and electrically connected in series to form a first layer sub-cell string;
a second layer of semiconductor material having an n-type region, a p-type region, and a second band-gap energy; and
a plurality of second layer sub-cells formed in the second layer along a second axis that is not perpendicular with the first axis and electrically connected in series to form a second layer sub-cell string, wherein the first layer sub-cell string and the second layer sub-cell string are electrically connected in parallel to form the two-terminal, monolithic, tandem photonic device.
42. A two-terminal, monolithic, tandem photonic device as defined in claim 41 , wherein the outer circumferential shapes of the first layer sub-cells and the second layer sub-cells are substantially the same shape.
43. A two-terminal, monolithic, tandem photonic device as defined in claim 41 , wherein the second layer of semiconductor material is grown on the first layer of semiconductor material.
44. A two-terminal, monolithic, tandem photonic device as defined in claim 43 , wherein the second layer of semiconductor material is grown epitaxially on the first layer of semiconductor material.
45. A two-terminal, monolithic, tandem photonic device as defined in claim 41 , wherein the first layer of semiconductor material and second layer of semiconductor material are physically bonded together.
46. A method of forming a multi-layer photonic semiconductor device, the method comprising the steps of:
forming a first layer of semiconductor material having a first band-gap energy on a substrate, the first layer including a first conductivity-type region and a second conductivity-type region on a substrate;
forming a second layer of semiconductor material having a second band-gap energy on the first layer, the second layer including a first conductivity-type region and a second conductivity-type region;
forming a plurality of isolation trenches through the first and second layers;
forming a plurality of electrical interconnects at least partially within the isolation trenches between conductivity-type regions in the first layer of semiconductor material; and
forming a plurality of electrical interconnects at least partially within the isolation trenches between conductivity-type regions in the second layer of semiconductor material.
47. A method of forming a multi-layer photonic semiconductor device as defined in claim 46 , wherein the second layer of semiconductor materials is formed epitaxially on the first layer of semiconductor material.
48. A method of forming a multi-layer photonic semiconductor device as defined in claim 46 , wherein the isolation trenches are formed substantially in parallel with one another.
49. A method of forming a photonic semiconductor device in a semiconductor structure having at least two semiconductor layers, each semiconductor layer including a first conductivity-type region and a second conductivity-type region, the method comprising the steps of:
forming a plurality of isolation trenches through the first and second semiconductor layers, the isolation trenches dividing the semiconductor structure into a plurality of sub-cell stacks, each stack including a sub-cell formed in the first semiconductor layer arid a sub-cell formed in the second semiconductor layer;
forming a plurality of first layer electrical interconnects at least partially within the isolation trenches between conductivity-type regions of sub-cells formed in the first semiconductor layer; and
forming a plurality of second layer electrical interconnects at least partially within the isolation trenches between conductivity-type regions of sub-cells formed in the second semiconductor layer.
50. A method of forming a photonic semiconductor device as defined in claim 49 , wherein the step of forming the first layer electrical interconnects includes forming at least one electrical interconnect between like conductivity-type regions of sub-cells formed in the second layer.
51. A method of forming a photonic semiconductor device as defined in claim 49 , wherein the step of forming the plurality of isolation trenches includes forming at least two substantially linear isolation trenches that are not parallel with one another.
52. A method of forming a photonic semiconductor device as defined in claim 49 , wherein the step of forming a plurality of isolation trenches includes:
forming a first isolation trench through the first and second layers along a first axis;
forming a second isolation trench through the first and second layers along a second axis, the second axis being parallel with the first axis;
forming a third isolation trench through the first and second layers along a third axis, the third axis being non-parallel with the first axis;
forming at least one electrical interconnect in the first isolation trench between conductivity-type regions in two sub-cells formed in the first layer of semiconductor material;
forming at least one interconnect in the second isolation trench between conductivity-type regions in two sub-cells formed in the first layer of semiconductor material; and
forming at least one interconnect in the third isolation trench between conductivity-type regions in two sub-cells formed in the second layer of semiconductor material.
53. A method of forming a two terminal, photonic device in a semiconductor structure having at least a first semiconductor layer and a second semiconductor layer, each semiconductor layer including a first conductivity-type region and a second conductivity-type region, the method comprising the steps of:
forming a plurality of first layer sub-cells in the first semiconductor layer along a first axis;
electrically connecting the plurality of first layer sub-cells in series to form a first layer sub-cell string;
forming a plurality of second layer sub-cells in the second semiconductor layer along a second axis that is not perpendicular with the first axis;
electrically connecting the plurality of second layer sub-cells in series to form a second layer sub-cell string; and
electrically connecting the first layer sub-cell string and the second layer sub-cell strings together in parallel.
54. A method of forming a two terminal, photonic device as defined in claim 53 , wherein the semiconductor layers are lattice-matched.