In a Schottky solar cell, consider using an opaque metal on top of the bulk of semiconductor.
Depletion region exists mostly between the metal and semiconductor, and due to the opaque metal, therefore, solar illumination cannot reach the depletion region. Therefore, no electron and hole are created in this region. However, electron and hole can be created in other areas in the bulk of semiconductor (outside of depletion region). Can these electron have any effect in creation of photogenerated current?
Dear Amirhossein,
welcome,
Your question is already answered in reference books of electronic devices. Please refer for example to the book physics and technology of electron devices by S.M.Sze. It contains a a description of operation of such MS soar cells.
It is so that the incident solar radiation will penetrate the material in the window regions between the metal stripes which are opaque as you said. The penetration depth depends on the wavelength of the incident radiation and the absorption coefficient of the material. Yes the shorter wave length radiation will be absorbed near he surface while the longer wavelength penetrates in the depth.
all of them generate e-h pairs causing an excess of electrons and holes in the material.
The electrons and holes generated inside the field region of the junction will be separated by this field such the electrons will be swept to the cathode while the holes will be swept to the anode. The electrons hole pairs generated out side the field region will diffuse to the field region because of the concentration gradient towards the field region. When they reach the drift region they will be separated similar to those generated inside the field region.
So, as you see the effect is exactly similar to the that occurring in the p-n junction.
The difference will be in the dark current. The current here is a majority carrier current with the injection over barrier limiting the dark current.
If you want to produce a field region over the whole surface and at the same time passing light to the active material you can either;
Cover the whole surface of the material with very thin metal layer,
or in case of silicon you can invert the surface region by just growing silicon oxide on it. The positive fixed charge at the oxide silicon interface can invert the p-substrate material into n-type, resulting in an induced n-p junction.
For more details see the reference given at the beginning of my comment.
wish you success
Dear Amirhossein,
welcome,
Your question is already answered in reference books of electronic devices. Please refer for example to the book physics and technology of electron devices by S.M.Sze. It contains a a description of operation of such MS soar cells.
It is so that the incident solar radiation will penetrate the material in the window regions between the metal stripes which are opaque as you said. The penetration depth depends on the wavelength of the incident radiation and the absorption coefficient of the material. Yes the shorter wave length radiation will be absorbed near he surface while the longer wavelength penetrates in the depth.
all of them generate e-h pairs causing an excess of electrons and holes in the material.
The electrons and holes generated inside the field region of the junction will be separated by this field such the electrons will be swept to the cathode while the holes will be swept to the anode. The electrons hole pairs generated out side the field region will diffuse to the field region because of the concentration gradient towards the field region. When they reach the drift region they will be separated similar to those generated inside the field region.
So, as you see the effect is exactly similar to the that occurring in the p-n junction.
The difference will be in the dark current. The current here is a majority carrier current with the injection over barrier limiting the dark current.
If you want to produce a field region over the whole surface and at the same time passing light to the active material you can either;
Cover the whole surface of the material with very thin metal layer,
or in case of silicon you can invert the surface region by just growing silicon oxide on it. The positive fixed charge at the oxide silicon interface can invert the p-substrate material into n-type, resulting in an induced n-p junction.
For more details see the reference given at the beginning of my comment.
wish you success
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