SURFACE MOUNT SOLAR CELL WITH INTEGRATED COVERGLASS
Photovoltaic cells, methods for fabricating surface mount multijunction photovoltaic cells, methods for assembling solar panels, and solar panels comprising photovoltaic cells are disclosed. The surface mount multijunction photovoltaic cells include through-wafer-vias for interconnecting the front surface epitaxial layer to a contact pad on the back surface. The through-wafer-vias are formed using a wet etch process that removes semiconductor materials non-selectively without major differences in etch rates between heteroepitaxial III-V semiconductor layers.
1 . A surface mount multijunction photovoltaic cell, comprising:
a substrate having a front substrate surface and a back substrate surface;
a heteroepitaxial layer overlying the front substrate surface;
a first portion of an antireflection coating overlying a first portion of the heteroepitaxial layer;
a patterned cap region overlying a second portion of the heteroepitaxial layer;
a through-wafer-via formed through the substrate and through the heteroepitaxial layer and electrically interconnecting the front side metal and the front surface solder pad;
a second portion of the antireflection coating overlying a third portion of the heteroepitaxial layer and disposed on sidewalls of the through-wafer-via;
a passivation layer underlying a portion of the back substrate;
a front surface solder pad underlying a portion of the passivation layer;
a front side metal overlying the patterned cap region, and the second portion of the antireflection coating, wherein the front side metal and the front surface solder pad are electrically interconnected;
a backside metal electrically interconnected to the back substrate surface;
an optical adhesive overlying the first portion of the antireflection coating, the patterned cap region, and the front side metal; and
a coverglass overlying the optical adhesive.
2 . The surface mount multijunction photovoltaic cell of claim 1 , wherein the substrate is less than 150 μm thick.
3 . The surface mount multijunction photovoltaic cell of claim 1 , wherein the substrate is less than 100 μm thick.
4 . The surface mount multijunction photovoltaic cell of claim 1 , wherein the surface mount multijunction photovoltaic cell is characterized by a unit mass per area of less than 0.09 g/cm 2 .
5 . The surface mount multijunction photovoltaic cell of claim 1 , wherein the heteroepitaxial layer comprises at least two junctions.
6 . The surface mount multijunction photovoltaic cell of claim 1 , wherein the sidewalls have smooth surfaces and the back substrate surface is free of pitting.
7 . The surface mount multijunction photovoltaic cell of claim 1 , further comprising a metal filling the through-wafer-via.
8 . The surface mount multijunction photovoltaic cell of claim 1 , wherein the heteroepitaxial layer comprises at least one dilute nitride junction.
9 . The surface mount multijunction photovoltaic cell of claim 1 , wherein the at least one dilute nitride junction comprises GaInNAsSb, GaInNAsBi, GaInNAsSbBi, GaInNAs, GaNAsSb, GaNAs, GaNAsBi, or GaNAsSbBi.
10 . The surface mount multijunction photovoltaic cell of claim 9 , wherein, the at least one dilute nitride junction comprises Ga 1-x In x N y As 1-y-z Sb z ; and
the content values for x, y, and z are within a range from 0.03≦x≦0.22, 0.007≦y≦0.055 and 0.001≦z≦0.05.
11 . The surface mount multijunction photovoltaic cell of claim 9 , wherein the at least one dilute nitride junction comprises Ga 1-x In x N y As 1-y-z Sb z having an antimony content within a range from 0.004≦z≦0.02, 0.005≦z≦0.018, 0.006≦z≦0.016, 0.008≦z≦0.015, 0.01≦z≦0.018, 0.01≦z≦0.014, 0.004≦z≦0.014, or 0.004≦z≦0.01.
12 . The surface mount multijunction photovoltaic cell of claim 9 , wherein the at least one dilute nitride junction comprises Ga 1-x In x N y As 1-y-z Sb z having a nitrogen content within a range from 0.02≦y≦0.10, 0.021≦y≦0.09, 0.024≦y≦0.085, 0.026≦y≦0.08, 0.03≦y≦0.06, or 0.04≦y≦0.06.
13 . The surface mount multijunction photovoltaic cell of claim 9 , wherein the at least one dilute nitride junction comprises Ga 1-x In x N y As 1-y-z Sb z having:
an antimony content within a range from 0.004≦z≦0.02, 0.005≦z≦0.018, 0.006≦z≦0.016, 0.008≦z≦0.015, 0.01≦z≦0.018, 0.01≦z≦0.014, 0.004≦z≦0.014, or 0.004≦z≦0.01; and
a nitrogen content within a range from 0.02≦y≦0.10, 0.021≦y≦0.09, 0.024≦y≦0.085, 0.026 ≦y≦0.08, 0.03≦y≦0.06, or 0.04≦y≦0.06.
14 . The surface mount multijunction photovoltaic cell of claim 1 , wherein the substrate comprises Ge or GaAs.
15 . A photovoltaic module comprising a plurality of the surface mount multijunction photovoltaic cells of claim 1 .
16 . The photovoltaic module of claim 15 , comprising:
an interconnection substrate; and
wherein the plurality of surface mount multijunction photovoltaic cells are mounted to the interconnection substrate.
17 . The photovoltaic module of claim 16 , wherein the interconnection substrate comprises:
interconnects between each of the plurality of surface mount multijunction photovoltaic cells; and
a plurality of bypass diodes, wherein each of the plurality of bypass diodes is interconnected to one or more of the plurality of surface mount multijunction photovoltaic cells,
wherein each of the plurality of bypass diodes is mounted to the interconnection substrate.
18 . The photovoltaic module of claim 15 , wherein,
the photovoltaic module comprises a front surface area; and
the plurality of surface mount multijunction photovoltaic cells cover at least 70% of the front surface area.
19 . A power system comprising at least one photovoltaic module of claim 15 .
20 . A method of fabricating a photovoltaic module, comprising interconnecting at least one surface mount multijunction photovoltaic cell of claim 1 to an interconnection substrate.
21 . The method of claim 20 , wherein interconnecting comprises surface mounting.