Understanding the Optics of Industrial Black Silicon

Industrial scale black silicon texturing has become a topic of increasing importance as a method for enabling lower cost multicrystalline silicon wafers through diamond wire sawing, as well as for its potential to provide improved efficiencies through enhanced optical characteristics. Two different texturing processes have emerged as candidates for mainstream industrial uptake, metal catalyzed chemical etching (MCCE) and reactive ion etching (RIE). However, these techniques can produce substantially different textures and both provide a wide parameter space allowing for various feature shapes and sizes to be produced. The surface texture not only determines the total reflectance of a solar cell, but also impacts the light trapping and subsequent absorption through scattering. Here, we carry out a detailed analysis on a representative range of both MCCE and RIE textures on multiple substrate types in order to further develop the fundamental understanding of how these specific surface morphologies impact the optical characteristics. This will better enable integration with other process conditions as well as optimization between optical and electrical requirements.