Novel Monocrystalline Silicon Texturing for supporting nano- to polycrystalline layers

Abstract

Crystalline silicon tandems with perovskites, CIGS and nanocrystalline silicon, as well as the TOPcon design are incompatible with the conventional pyramidal surface texture of silicon. Three texturing approaches, using alkaline and/or acidic wet chemical etches, are investigated in this work, that can lead to the crack-free growth of a nano- to poly-crystalline silicon material on textured surfaces. Without acidic smoothening, the fraction of <111> pyramidal surface coverage has to remain relatively small to prevent crack formation during crystalline growth. Applying an acidic etch as a function of time continuously smoothens surface features. This shifts the reflection to wider scattering angles and results in higher total reflected intensity with respect to the conventional texture, making it an interesting option for a wide variety of tandem pv applications. Finally we demonstrate crater like features on a <100> monocrystalline silicon surface using an etching process inlcuding a sacrificial layer. These craters increases light scattering into wider angles, but to a lesser extent than the former approach.