Learn about black silicon and its applications
The origin of the name black silicon is that as seen by the human eye, the color is black. Because of the microstructure on the surface, black silicon can absorb nearly 100% of the incident light, and very little light is reflected, so it appears black to the human eye.
The unique optical and semiconductor properties of black silicon materials have brought a wide range of applications to photoelectric sensors (photodetectors, thermal imaging cameras, etc.), such as low-light cameras that work in the visible and near-infrared dual-bands, bringing great benefits to civilian and military applications. Come to many conveniences.
One of the most attractive properties of black silicon is its fairly low reflectivity and wide-angle absorption capabilities over a wide spectral range. The reflectivity of black silicon can usually reach less than 10%, which is very useful for nanocones or nanowires. The special structure of diameter ratio can further reduce the average reflectivity to less than 3% by optimizing process parameters.
With the development of silicon fine processing technology, the microstructure of black silicon has developed from the earliest nanocone structure processed by femtosecond laser to pyramid, hole, nanowire and composite structures.
After years of exploration, various processing systems have been established for black silicon processing methods. Commonly used methods include femtosecond laser method, electrochemical etching method, reactive ion etching method, acid method, alkali method, metal-assisted etching method, etc. method. Each processing method has different microstructure morphology and available optical properties.
At the same time, the definition of black silicon has gradually expanded. It is no longer limited to microstructured silicon processed by femtosecond laser, and the color is not limited to black. As long as it has obvious light trapping ability, it can be called microstructured silicon. It is black silicon material.
By controlling the characteristic structural size of multilayer porous silicon, researchers artificially control changes in its refractive index. The silicon surface has different absorption effects for different light, and ultimately different colors appear under human eyes. This technical solution can be applied to a four-quadrant detector, so that each quadrant exhibits different spectral response characteristics.
As a new material, black silicon has many excellent properties and has been used in many fields, such as extremely high light absorption rate and light sensitivity, which can be used as the absorbing layer of photodetectors; using black silicon’s anti-reflection properties and wide angle Characteristics such as absorption can improve device performance such as photoelectric response rate and response spectral range; black silicon’s pyramidal structure has excellent field emission characteristics, so it can be used as a field emission material. Black silicon also has excellent photoemission properties. Due to its luminescent properties, it can be used as a photoluminescent material; using the ultra-high specific surface area of black silicon, it can be used as a solid adhesive or heat dissipation structure between silicon materials.
In many applications, black silicon materials have shown their great value in improving the photovoltaic efficiency of industrial crystalline silicon solar cells. With the explosive development of diamond wire cutting silicon wafer technology, the damage layer during silicon wafer cutting has been greatly reduced, and thinner monocrystalline or polycrystalline silicon wafers can also be provided, which has greatly promoted the vigorous development of the photovoltaic industry and improved the performance of devices. Photoelectric conversion efficiency, photovoltaic cells are in urgent need of front surface technology with low reflectivity and wide-angle absorption and structural design with enhanced absorption. Black silicon technology shows natural coupling in the photovoltaic field.