Inverted GaInP/GaAs Three-Terminal Heterojunction Bipolar Transistor Solar Cell.

Here we present the experimental results of an inverted three-terminal heterojunction bipolar transistor solar cell (HBTSC) made of GaInP/GaAs. The inverted growth and processing enable contacting the intermediate layer (base) from the bottom, which improves the cell performance by reducing shadow factor and series resistance at the same time. With this prototype we show that an inverted processing of a three-terminal solar cell is feasible and pave the way for the application of epitaxial lift-off, substrate reuse and mechanical stacking to the HBTSC which can eventually lead to a low-cost high-efficiency III-V-on-Si HBTSC technology.