Described herein are methods of fabricating solar cells. In an example, a method of fabricating a solar cell includes forming an amorphous dielectric layer on the back surface of a substrate opposite a light-receiving surface of the substrate. The method also includes forming a microcrystalline silicon layer on the amorphous dielectric layer by plasma enhanced chemical vapor deposition (PECVD). The method also includes forming an amorphous silicon layer on the microcrystalline silicon layer by PECVD. The method also includes annealing the microcrystalline silicon layer and the amorphous silicon layer to form a homogeneous polycrystalline silicon layer from the microcrystalline silicon layer and the amorphous silicon layer. The method also includes forming an emitter region from the homogeneous polycrystalline silicon layer.

An encapsulated integrated photodetector waveguide structures with alignment tolerance and methods of manufacture are disclosed. The method includes forming a waveguide structure bounded by one or more shallow trench isolation (STI) structure(s). The method further includes forming a photodetector fully landed on the waveguide structure.

A method of fabricating a passivated contact for a photovoltaic cell includes depositing a tunneling oxide layer on a first face of a substrate. An amorphous silicon layer is then deposited on top of the tunneling oxide layer. An aluminum layer is screen printed on top of the amorphous silicon layer. The aluminum layer is configured to serve as a crystallization catalyst for the amorphous silicon layer. The amorphous silicon layer and the aluminum layer are then heated to a crystallization temperature that is configured to cause the amorphous silicon to crystallize and to sinter the aluminum layer.

A P-type solar cell comprises a layer stack with: a back electrode, a p-type semiconductor absorber layer disposed on the back electrode, a crystalline cadmium sulfide (CdS) layer disposed on the absorber layer, and a front electrode disposed on the side of the layer stack opposite of the back electrode. The CdS layer has Cu-doping and a layer thickness between 50 and 300 . A method for producing a p-type solar cell comprises: providing a p-type photoactive semiconductor absorber layer, etching the surface of the absorber layer such that crystallographic unevenness and pinholes are reduced, depositing a CdS layer on the absorber layer, with a layer thickness between 50 and 200 , heating at least the CdS layer to recrystallize the CdS layer, and optionally placing on the absorber layer a Cu-containing layer different from the CdS layer, either after etching or after the application of the CdS layer.

A P-type solar cell comprises a layer stack with: a back electrode, a p-type semiconductor absorber layer disposed on the back electrode, a crystalline cadmium sulfide (CdS) layer disposed on the absorber layer, and a front electrode disposed on the side of the layer stack opposite the back electrode. The CdS layer has Cu-doping and a layer thickness between 50 and 300 . A method for producing a p-type solar cell comprises: providing a p-type photoactive semiconductor absorber layer, etching the surface of the absorber layer such that crystallographic unevenness and pinholes are reduced, depositing a CdS layer on the absorber layer, with a layer thickness between 50 and 200 , applying heat to at least the CdS layer to recrystallize the CdS layer, and optionally placing on the absorber layer a Cu-containing layer different from the CdS layer, either after etching or after the application of the CdS layer.

Various particular embodiments include a method for forming a photodetector, including: forming a structure including a barrier layer disposed between a layer of doped silicon (Si) and a layer of germanium (Ge), the barrier layer including a crystallization window; and annealing the structure to convert, via the crystallization window, the Ge to a first composition of silicon germanium (SiGe) and the doped Si to a second composition of SiGe.

An encapsulated integrated photodetector waveguide structures with alignment tolerance and methods of manufacture are disclosed. The method includes forming a waveguide structure bounded by one or more shallow trench isolation (STI) structure(s). The method further includes forming a photodetector fully landed on the waveguide structure.

Photodiode structures and methods of manufacture are disclosed. The method includes forming a waveguide structure in a dielectric layer. The method further includes forming a Ge material in proximity to the waveguide structure in a back end of the line (BEOL) metal layer. The method further includes crystallizing the Ge material into a crystalline Ge structure by a low temperature annealing process with a metal layer in contact with the Ge material.

Photodiode structures and methods of manufacture are disclosed. The method includes forming a waveguide structure in a dielectric layer. The method further includes forming a Ge material in proximity to the waveguide structure in a back end of the line (BEOL) metal layer. The method further includes crystallizing the Ge material into a crystalline Ge structure by a low temperature annealing process with a metal layer in contact with the Ge material.

An encapsulated integrated photodetector waveguide structures with alignment tolerance and methods of manufacture are disclosed. The method includes forming a waveguide structure bounded by one or more shallow trench isolation (STI) structure(s). The method further includes forming a photodetector fully landed on the waveguide structure.