Abstract
A semiconductor device used for conversion between light and electricity, comprising a semiconductor stack comprising an upper surface; and an upper electrode formed on the semiconductor stack and comprising a first linear electrode and second electrodes, wherein the first linear electrode is closer to a center of the upper surface than the second electrodes, wherein the first linear electrode has a width varying along a first direction thereof, and each of the second electrodes has a uniform width along a second direction thereof.
Claims
1. A semiconductor device used for conversion between light and electricity, comprising: a semiconductor stack comprising an upper surface; and an upper electrode formed on the semiconductor stack and comprising a first linear electrode and second electrodes, wherein the first linear electrode is closer to a center of the upper surface than the second electrodes, wherein the first linear electrode has a width varying along a first direction thereof, and each of the second electrodes has a uniform width along a second direction thereof.
2. The semiconductor device of claim 1, wherein the second electrodes are parallel to each other.
3. The semiconductor device of claim 1, wherein the upper electrode further comprises a collector electrode on a side of the upper surface.
4. The semiconductor device of claim 3, wherein the first linear electrode and the second electrodes are closer to the center of the upper surface than the collector electrode.
5. The semiconductor device of claim 3, wherein the collector electrode comprises a first collector electrode and a second collector electrode away from the first collector electrode, and the first collector electrode is parallel to the second collector electrode.
6. The semiconductor device of claim 5, wherein the first linear electrode and the second electrodes locate between the first collector electrode and the second collector electrode.
7. The semiconductor device of claim 1, wherein the upper electrode further comprises more than one first linear electrode, and the first linear electrodes are parallel with each other.
8. The semiconductor device of claim 1, wherein the width of the first linear electrode is larger than 50 m.
9. The semiconductor device of claim 1, further comprising an anti-reflective layer formed on the upper surface of the semiconductor stack, wherein the anti-reflective layer comprises a dielectric material.
10. The semiconductor device of claim 1, wherein the semiconductor stack comprises a lower surface opposite to the upper surface, and a lower electrode is formed on the lower surface of the semiconductor stack.
11. The semiconductor device of claim 3, wherein the second electrodes are directly connected to the collector electrode.
12. The semiconductor device of claim 1, wherein the first linear electrode is connected to one of the second electrodes.
13. The semiconductor device of claim 1, wherein the width of the first linear electrode in the center of the upper surface is smaller than that in an area near the center of the upper surface.
14. A semiconductor device used for conversion between light and electricity, comprising: a semiconductor stack comprising an upper surface; and an upper electrode comprising a first linear electrode and second electrodes, wherein the first linear electrode is closer to a center of the upper surface than the second electrodes, wherein the first linear electrode has a various width, and the second electrodes have a uniform pitch there between.
15. The semiconductor device of claim 14, wherein the uniform pitch between the second electrodes is smaller than 300 m.
16. The semiconductor device of claim 14, wherein the second electrodes are parallel to each other.
17. The semiconductor device of claim 14, wherein each of the second electrodes has a uniform width.
18. The semiconductor device of claim 14, wherein the upper electrode further comprises a collector electrode on a side of the upper surface.
19. The semiconductor device of claim 14, wherein the first linear electrode is connected to one of the second electrodes.
20. The semiconductor device of claim 14, wherein a width of the first linear electrode in the center of the upper surface is smaller than that in an area near the center of the upper surface.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 illustrates a diagram of a conventional concentrator module;
[0011] FIG. 2 illustrates a top-viewed diagram of a conventional photovoltaic cell;
[0012] FIG. 2A illustrates a partial enlargement of a top-viewed diagram of a conventional photovoltaic cell;
[0013] FIG. 3 illustrates an example of a conventional photovoltaic cell with a conventional concentrator module;
[0014] FIG. 4 illustrates a cross-sectional diagram of a concentrated photovoltaic cell in accordance with a first embodiment of the present application;
[0015] FIG. 5 illustrates a top-viewed diagram of a concentrated photovoltaic cell in accordance with a first embodiment of the present application;
[0016] FIG. 6 illustrates a partial enlargement of a top-viewed diagram of a concentrated photovoltaic cell in accordance with a first embodiment of the present application;
[0017] FIG. 7 illustrates a top-viewed diagram of a concentrated photovoltaic cell in accordance with a second embodiment of the present application;
[0018] FIG. 8 illustrates a partial enlargement of a top-viewed diagram of a concentrated photovoltaic cell in accordance with a second embodiment of the present application;
[0019] FIG. 9 illustrates a top-viewed diagram of a concentrated photovoltaic cell in accordance with a third embodiment of the present application;
[0020] FIG. 10 illustrates a partial enlargement of a top-viewed diagram of a concentrated photovoltaic cell in accordance with a third embodiment of the present application;
[0021] FIG. 11 illustrates a top-viewed diagram of a concentrated photovoltaic cell in accordance with a fourth embodiment of the present application;
[0022] FIG. 12 illustrates a partial enlargement of a top-viewed diagram of a concentrated photovoltaic cell in accordance with a fourth embodiment of the present application;
[0023] FIG. 13 illustrates a top-viewed diagram of a concentrated photovoltaic cell in accordance with a fifth embodiment of the present application; and
[0024] FIG. 14 illustrates a partial enlargement of a top-viewed diagram of a concentrated photovoltaic cell in accordance with a fifth embodiment of the present application.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0025] The embodiment of the application is illustrated in detail, and is plotted in the drawings. The same or the similar part is illustrated in the drawings and the specification with the same number.
[0026] FIG. 4 illustrates a cross-sectional diagram of a concentrated photovoltaic cell 20 in accordance with a first embodiment of the present application. FIG. 5 illustrates a top-viewed diagram of the concentrated photovoltaic cell 20 in accordance with the first embodiment of the present application. FIG. 4 illustrates the cross-sectional diagram alone line X-X of FIG. 5. As shown in FIG. 4, the concentrated photovoltaic cell 20 is operable to absorb a light, such as sunlight. The concentrated photovoltaic cell 20 comprises a semiconductor stack 210 comprising an upper surface S1 and a lower surface S2 opposite to the upper surface S1, wherein the upper surface S1 is formed near a side where the light incident thereon and operable to absorb the light, and the light incident on the upper surface S1 comprises a light intensity distribution; an upper electrode 200 formed on the upper surface S1 of the semiconductor stack 210; a lower electrode 209 formed on the lower surface S2 of the semiconductor stack 210; and an anti-reflective layer 201 formed on the upper surface S1 of the semiconductor stack 210. The anti-reflective layer 201 comprises dielectric materials, such as silicon nitride (SiN.sub.x), silicon oxide (SiO.sub.2), aluminum oxide (Al.sub.2O.sub.3), or titanium oxide (TiO.sub.x). The anti-reflective layer 201 reduces reflection of the light on the upper surface S1. The material of the upper electrode 200 and the lower electrode 209 comprises metal, such as titanium, platinum, nickel, gold, or silver, which can be formed on the semiconductor stack 210 by electroplating, vapor deposition, or sputter.
[0027] The semiconductor stack 210 comprises one junction or multiple junctions. As shown in FIG. 4, the semiconductor stack 210 comprises a window layer 205 formed on a side near the anti-reflective layer 201, a top subcell 206, a middle subcell 207, and a bottom subcell 208 formed on a side near the lower electrode 209. The material of the semiconductor stack 210 comprises group III or group V element, such as arsenic (As), gallium (Ga), aluminum (Al), indium(In), phosphorus (P), or nitrogen (N). The semiconductor stack 210 may be formed by a known epitaxy method such as metallic-organic chemical vapor deposition (MOCVD) method, a molecular beam epitaxy (MBE) method, a hydride vapor phase epitaxy (HVPE) method, sputtering, or electrical plating.
[0028] The window layer 205 directs the light incident on the upper surface S1 of the semiconductor stack 210 towards the top subcell 206, the middle subcell 207, and the bottom subcell 208. The top subcell 206, the middle subcell 207, and the bottom subcell 208 absorb the light and convert that into an electrical current. The upper electrode 200 and the lower electrode 209 collect and export the electrical current provided from the top subcell 206, the middle subcell 207, and the bottom subcell 208.
[0029] As shown in FIG. 5, the upper electrode 200 comprises a plurality of collector electrodes 202 and a plurality of grid electrodes 203. An electrode pattern of the upper electrode 200 is related with resistance, fill factor (FF), or short-circuit current (I.sub.sc) of the concentrated photovoltaic cell 20. A width or a pitch of the plurality of grid electrodes 203 can be adjusted to change the light shielding area of the upper electrode 200. FIG. 5 illustrates the top-viewed diagram of the concentrated photovoltaic cell 20 in accordance with the first embodiment of the present application. The upper electrode 200 comprises an electrode pattern approximately corresponding to an intensity distribution of the light absorbed by the upper surface S1, wherein the light intensity distribution comprises a high light-concentrated area I having a first light intensity and a low light-concentrated area II having a second light intensity, wherein the second light intensity is lower than the first light intensity. The electrode pattern comprises a first electrode area 204 and a second electrode area 201 different from the first electrode area 204. The first electrode area 204 and the second electrode area 201 are approximately corresponding to the high light-concentrated area I and the low light-concentrated area II respectively. The first electrode area 204 comprises an area disposed on a center area of the upper surface S1. The plurality of grid electrodes 203 and the plurality of collector electrodes 202 are formed by lithography, wherein the plurality of collector electrodes 202 comprises a width larger than 50 m, preferably larger than 100 m.
[0030] As shown in FIG. 5, a ratio of the first electrode area 204 and the upper surface S1 is not larger than 80%. An optical concentrator (not shown) having a concentration magnification, such as at least 200 suns above, is disposed on the semiconductor stack 210 near a side where the sunlight incident thereon. The high light-concentrated area I comprises a concentration magnification larger than that of the optical concentrator, such as 200 suns above; and the low light-concentrated area II comprises a concentration magnification lower than that of the optical concentrator, such as 200 suns below. The plurality of grid electrodes 203 and the plurality of collector electrodes 202 are perpendicular to each other, and the grid electrodes 203 are parallel to each other. The width of the plurality of grid electrodes 203 in the first electrode area 204 is smaller than that in the second electrode area 201. The pitch of the plurality of grid electrodes 203 in the first electrode area 204 is equal to that in the second electrode area 201.
[0031] FIG. 6 illustrates a partial enlargement of a top-viewed diagram of the plurality of grid electrodes 203 shown in FIG. 5. As shown in FIG. 6, the pitch of a plurality of grid electrodes 203a in the first electrode area 204 (the high light-concentrated area I) is d1, the pitch of a plurality of grid electrodes 203b in the second electrode area 201 (the low light-concentrated area II) is d2. In the embodiment, the width w1 of the plurality of grid electrodes 203a in the first electrode area 204 is smaller than the width w2 in the second electrode area 201, and the pitch d1 of the plurality of grid electrodes 203a is equal to the pitch d2 of the plurality of grid electrodes 203b. The pitch d1 of the plurality of grid electrodes 203a in the first electrode area 204 or the pitch d2 of the plurality of grid electrodes 203b in the second electrode area 201 is between 50 m300 m, preferably between 90 m200 m. In the embodiment, the width w1 of the plurality of grid electrodes 203 in the first electrode area 204 is smaller than the width w2 of the plurality of grid electrodes 203 in the second electrode area 201, which reduces light shielding area of the plurality of grid electrodes 203 in the high light-concentrated area I and increases short-circuit current (I.sub.sc) of the concentrated photovoltaic cell 20.
[0032] FIG. 7 illustrates a top-viewed diagram of a concentrated photovoltaic cell 20 in accordance with a second embodiment of the present application. FIG. 8 illustrates a partial enlargement of a top-viewed diagram of a plurality of grid electrodes 203 shown in FIG. 7. As shown in FIG. 8, the pitch d1 of a plurality of grid electrodes 203a in the first electrode area 204 (the high light-concentrated area I) is smaller than the pitch d2 of a plurality of grid electrodes 203b in the second electrode area 201 (the low light-concentrated area II). The pitch d1 of the plurality of grid electrodes 203a in the first electrode area 204 (the high light-concentrated area I) is larger than 50 m, preferably larger than 90 m. The pitch d2 of the plurality of grid electrodes 203b in the second electrode area 201 (the low light-concentrated area II) is smaller than 300 m, preferably smaller than 200 m. In the embodiment, the width w1 of the plurality of grid electrodes 203a in the first electrode area 204 is smaller than the width w2 of the plurality of grid electrodes 203b in the second electrode area 201, which reduces light shielding area of the plurality of grid electrodes 203a in the high light-concentrated area I. The pitch d2 of the plurality of grid electrodes 203 in the second electrode area 201 is larger than the pitch d1 of the plurality of grid electrodes 203 in the first electrode area 204, which reduces light shielding area of the plurality of grid electrodes 203 in the low light-concentrated area II, and increases short-circuit current (I.sub.sc) of the concentrated photovoltaic cell 20.
[0033] FIG. 9 illustrates a top-viewed diagram of a concentrated photovoltaic cell 20 in accordance with a third embodiment of the present application. FIG. 10 illustrates a partial enlargement of a top-viewed diagram of a plurality of grid electrodes 203 shown in FIG. 9. As shown in FIG. 10, the pitch d1 of a plurality of grid electrodes 203a in the first electrode area 204 (the high light-concentrated area I) is smaller than the pitch d2 of a plurality of grid electrodes 203b in the second electrode area 201 (the low light-concentrated area II). The pitch d1 of the plurality of grid electrodes 203a in the first electrode area 204 (the high light-concentrated area I) is larger than 50 m, preferably larger than 90 m. The pitch d2 of the plurality of grid electrodes 203b in the second electrode area 201 (the low light-concentrated area II) is smaller than 300 m, preferably smaller than 200 m. In the embodiment, the width w1 of the plurality of grid electrodes 203a in the first electrode area 204 is equal to the width w2 of the plurality of grid electrodes 203b in the second electrode area 201. In the embodiment, the pitch d2 of the plurality of grid electrodes 203 in the second electrode area 201 is larger than the pitch d1 of the plurality of grid electrodes 203 in the first electrode area 204, which reduces light shielding area of the plurality of grid electrodes 203 in the low light-concentrated area II, and increases short-circuit current (I.sub.sc) of the concentrated photovoltaic cell 20.
[0034] FIG. 11 illustrates a top-viewed diagram of a concentrated photovoltaic cell 20 in accordance with a fourth embodiment of the present application. FIG. 12 illustrates a partial enlargement of a top-viewed diagram of a plurality of grid electrodes 203 shown in FIG. 11. As shown in FIG. 12, the pitch d1 of a plurality of grid electrodes 203a in the first electrode area 204 (the high light-concentrated area I) is equal to the pitch d2 of a plurality of grid electrodes 203b in the second electrode area 201 (the low light-concentrated area II). The pitch d1 of the plurality of grid electrodes 203a in the first electrode area 204 or the pitch d2 of the plurality of grid electrodes 203b in the second electrode area 201 is between 50 m300 m, preferably between 90 m200 m. The width w1 of the plurality of grid electrodes 203a in the first electrode area 204 is smaller than the width w2 of the plurality of grid electrodes 203b in the second electrode area 201. In the embodiment, the plurality of grid electrodes 203b in the second electrode area 201 is connected to the collector electrode 202 and extends towards a direction away from the collector electrode 202, and the plurality of grid electrodes 203b is connected to the grid electrode 203a in the first electrode area 204. In other words, one side of the grid electrode 203b in the second electrode area 201 is connected to the collector electrode 202, and another side of the grid electrode 203b is connected to the grid electrode 203a in the first electrode area 204. The width w2 of the grid electrode 203b is larger than the width w1 of the grid electrode 203a, which reduces resistance loss when the photo-induced current flows from the high light-concentrated area I to the low light-concentrated area II.
[0035] FIG. 13 illustrates a top-viewed diagram of a concentrated photovoltaic cell 20 in accordance with a fifth embodiment of the present application. FIG. 14 illustrates a partial enlargement of a top-viewed diagram of a plurality of grid electrodes 203 shown in FIG. 13. As shown in FIG. 14, the pitch d1 of a plurality of grid electrodes 203a in the first electrode area 204 (the high light-concentrated area I) is smaller than the pitch d2 of a plurality of grid electrodes 203b in the second electrode area 201 (the low light-concentrated area II). The pitch d1 of the plurality of grid electrodes 203a in the first electrode area 204 (the high light-concentrated area I) is larger than 50 m, preferably larger than 90 m. The pitch d2 of the plurality of grid electrodes 203b in the second electrode area 201 (the low light-concentrated area II) is smaller than 300 m, preferably smaller than 200 m. The width w1 of the plurality of grid electrodes 203a in the first electrode area 204 is smaller than the width w2 of the plurality of grid electrodes 203b in the second electrode area 201. In the embodiment, the plurality of grid electrodes 203b in the second electrode area 201 is connected to the collector electrode 202 and extends towards a direction away from the collector electrode 202, and the grid electrodes 203b are respectively connected to the grid electrodes 203a in the first electrode area 204. In other words, one side of the grid electrode 203b in the second electrode area 201 is connected to the collector electrode 202, and another side of the grid electrode 203b is connected to the grid electrode 203a in the first electrode area 204. The width w2 of the grid electrode 203b is larger than the width w1 of the grid electrode 203a, which reduces resistance loss when the photo-induced current flows from the high light-concentrated area I to the low light-concentrated area II.
[0036] The principle and the efficiency of the present application illustrated by the embodiments above are not the limitation of the application. Any person having ordinary skill in the art can modify or change the aforementioned embodiments. Therefore, the protection range of the rights in the application will be listed as the following claims.
