Flexible silicon infrared emitter
An apparatus includes a flexible silicon (Si) substrate, such as a crystalline n-type substrate, and a heterostructure structure formed on the silicon substrate. The heterojunction structure includes a first layered structured deposited on a first side of the silicon substrate. The first layered structured includes a first amorphous intrinsic silicon layer, an amorphous n-type or p-type silicon layer, and a transparent conductive layer. The second layered structure includes a second amorphous intrinsic silicon layer, an amorphous p-type or n-type silicon layer, and a transparent conductive layer. The heterostructure structure is configured to operate as a photovoltaic cell and an infrared light emitting diode.
1. A method of forming a photovoltaic cell and a light emitting diode apparatus, the method comprising:
growing a flexible crystalline silicon substrate;
depositing a first layered structure on a first side of the flexible crystalline silicon substrate, the first layered structure including a first passivation layer, a first amorphous silicon layer doped as one of n-type or p-type, and a first transparent conductive layer;
treating a portion of the first passivation layer with a first hydrogen plasma treatment before depositing the first amorphous silicon layer and the first transparent conductive layer of the first layered structure on the flexible crystalline silicon substrate;
depositing a second layered structure on a second side of the flexible crystalline silicon substrate, the second layered structure including a second passivation layer, a second amorphous silicon layer doped as one of n-type or p-type, wherein the second amorphous silicon layer is doped to be an opposite type as the first amorphous silicon layer, and a second transparent conductive layer, the first layered structure and the second layered structure together forming a heterostructure on the flexible crystalline silicon substrate;
treating a portion of the second passivation layer with a second hydrogen plasma treatment before depositing the second amorphous silicon layer and the second transparent conductive layer of the second layered structure on the flexible crystalline silicon substrate; and
applying metallization to the apparatus for conducting electricity.
2. The method of claim 1 , wherein growing the flexible crystalline silicon substrate comprises growing the flexible crystalline substrate as a p-doped or n-doped substrate.
3. The method according to claim 1 , wherein growing the flexible crystalline silicon substrate comprises:
growing a first silicon substrate to a first thickness larger than 100 micrometers; and
reducing, through wet alkaline etching and chemical washes, the first silicon substrate to a second thickness of between a few micrometers and 100 micrometers to produce the flexible crystalline silicon substrate.
4. The method according to claim 1 , wherein applying the metallization comprises:
screen printing a first layer of silver over the first side of the flexible crystalline substrate in a grid pattern; and
sputter depositing a second layer of conductive metal plating over the second side of the flexible crystalline substrate.
5. The method according to claim 1 , wherein applying the metallization comprises:
copper plating the first side of the flexible crystalline substrate; and
sputter depositing a conductive metal reflector over the second side of the flexible crystalline substrate.
6. The method of claim 1 , further comprising:
depositing the first passivation layer by:
depositing a first intrinsic amorphous silicon layer before the first hydrogen plasma treatment;
depositing a second intrinsic amorphous silicon layer after the first hydrogen plasma treatment.
7. The method of claim 6 , wherein the second intrinsic amorphous silicon layer is thicker than the first intrinsic amorphous silicon layer.