Excess photo-carriers and cumulative Auger effects in GaAs–Ge quantum wells for high efficiency p–i (qw)–n solar cells

We report on carrier photo-excitation in GaAs–Ge quantum wells in the intrinsic region of p–i–n solar cells. In the process of the analysis, we solve for diffused photo-carriers in the quantum wells. We propose a wide gap/narrow gap/∼ 1 eV-gap via quantum well/narrow gap solar cell design. Our device model overcomes mobility problems (as is the case of III–N–V currently studied designs) and capitalizes on thermal escape of excess photo-excited carriers from quantum wells. We include the only significant effect of recombination losses via Auger Cooling on photo-excited carriers in intrinsic quantum wells, as found in the middle region of p–i–n solar cells, along with interface losses. We derive an explicit account of photo-carriers in quantum wells as a strong function of device parameters, Auger cumulative effect via a coefficient cn as follows:δn=nph+no,withnph∼cn−1/3.