Fabrication techniques for high-performance Si heterojunction (SHJ) microcells

Silicon heterojunction (SHJ) microcells offer a promising photovoltaic (PV) device for a wide range of micro-electronic applications due to their high performance potential. We examine two separate techniques for dicing SHJ microcells from bulk wafers: deep reactive ion etching (DRIE) and micro-laser cutting. We present the challenges and optimizations for each technique, as well as microcell performance for a 400µm x 400µm x 80µm microcell. Given the thickness of silicon wafers and the low face-to-edge area ratio for SHJ microcells of these dimensions, we consider varied illumination conditions for this structure. SHJ microcells are able to absorb photons along all surfaces; as such, we study microcell performance at each edge interface. We examine both modeled and experimental data of microcells across various lighting conditions and present high-performances for both sets of measurements.