Sputtered then evaporated back metal process for increased throughput
A method is described that includes sputtering multiple layers on a back surface of the photovoltaic structure, the photovoltaic structure being made of at least one group III-V semiconductor material, and evaporating, over the multiple layers, one or more additional layers including a metal layer, the back metal structure being formed by the multiple layers and the additional layers. A photovoltaic device is also described that includes a back metal structure disposed over a back surface of a photovoltaic structure made of a group III-V semiconductor material, the back metal structure including one or more evaporated layers disposed over multiple sputtered layers, the one or more evaporated layers including a metal layer. By allowing evaporation along with sputtering, tool size and costs can be reduced, including minimizing a number of vacuum breaks. Moreover, good yield and reliability, such as reducing dark line defects (DLDs), can also be achieved.
1. A photovoltaic device, comprising:
a photovoltaic structure made of a group III-V semiconductor material;
multiple sputtered layers disposed over a back surface of the photovoltaic structure, and
one or more evaporated layers including a metal layer and disposed over the multiple sputtered layers;
wherein the multiple sputtered layers and the one or more evaporated layers together form a back metal structure, and
wherein the multiple sputtered layers include a layer closest to the back surface of the photovoltaic structure, the layer being configured to adhere remaining layers of the multiple sputtered layers to the back surface of the photovoltaic structure.
2. The photovoltaic device of claim 1 , wherein the multiple sputtered layers include a layer made of a reflecting material.
3. The photovoltaic device of claim 1 , wherein the multiple sputtered layers include a layer that is closest to the one or more evaporated layers, the layer being configured to provide a migration barrier from the metal layer to the photovoltaic structure.
4. The photovoltaic device of claim 3 , wherein the layer from the multiple sputtered layers that is closest to the one or more additional evaporated layers has a thickness greater than 100 nanometers.
5. The photovoltaic device of claim 1 , wherein a thickness of the one or more evaporated layers is greater than a thickness of the multiple sputtered layers.
6. The photovoltaic device of claim 1 , further comprising one or more of an encapsulant layer, a glass or plastic layer, or an anti-reflective coating (ARC) disposed on a front side of the photovoltaic device and at least partially over a front surface of the photovoltaic structure.
7. The photovoltaic device of claim 1 , further comprising one or more of a dielectric layer, a glass or plastic layer, or an ARC disposed on a back side of the photovoltaic device and at least partially over the back surface of the photovoltaic structure.
8. The photovoltaic device of claim 1 , further comprising a window layer disposed over a front surface of the photovoltaic structure.
9. The photovoltaic device of claim 1 , further comprising a reflector disposed on a back side of the photovoltaic device and over the back metal structure.
10. The photovoltaic device of claim 1 , wherein the photovoltaic structure is a multi-junction structure that includes more than one sub-cell.