Nanophotovoltaic devices
View Patent ↗The present invention provides nanophotovoltaic devices having sizes in a range of about 50 nm to about 5 microns, and method of their fabrication. In some embodiments, the nanophotovoltaic device includes a semiconductor core, e.g., formed of silicon, sandwiched between two metallic layers, one of which forms a Schottky barrier junction with the semiconductor core and the other forms an ohmic contact therewith. In other embodiment, the nanophotovoltaic device includes a semiconductor core comprising a p-n junction that is sandwiched between two metallic layers forming ohmic contacts with the core.
1. A method of forming nanophotovoltaic devices, comprising
providing a silicon wafer having a buried oxide layer separating a thin silicon layer from the bulk of the wafer,
depositing a first metallic layer on an exposed surface of said thin silicon layer so as to form a schottky barrier junction with said silicon surface,
removing the oxide layer and the bulk portion of the wafer to generate a structure comprising said thin silicon layer and said metallic layer disposed on a surface thereof,
depositing a second metallic layer on an exposed surface of said thin silicon layer opposed to said first metallic layer to form an ohmic contact therewith,
applying a photoresist to one of said metallic layers,
holographically patterning said resist to generate a two-dimensional holographic recording therein,
developing said patterned photoresist to generate a pattern of exposed and unexposed portions, and
etching away the exposed portions to generate a plurality of nanophotovoltaic devices.
2. The method of claim 1 , wherein said step of holographically patterning the resist comprises
exposing the photoresist to a one-dimensional holographic line grating,
rotating the wafer by 90 degrees, and
exposing the photoresist to the line grating.
3. The method of claim 1 , wherein said step of holographically patterning the resist comprises:
exposing the photoresist to a two-dimensional grating pattern.
4. The method of claim 1 , wherein said holographic patterning provides a resolution of about 1000 nm.
5. The method of claim 1 , wherein the step of etching away the exposed portions comprises employing a dry etching process.
6. The method of claim 1 , further comprising attaching said wafer via said first metallic layer to a support wafer to facilitate performing the processing steps subsequent to said step of depositing a first metallic layer.
7. The method of claim 1 , further comprising utilizing a dissolvable adhesive to attach the wafer to the support wafer.
8. The method of claim 7 , further comprising removing said photoresist from said generated nanophotovoltaic devices.
9. The method of claim 8 , further comprising releasing said nanophotovoltaic devices from said support wafer.