Hot carriers in strain balanced quantum well solar cells

The incorporation of strain-balanced quantum wells into a GaAs solar cell extends the spectral response resulting in a photocurrent increase that can exceed the reduction in voltage performance, leading to higher overall efficiencies [1]. At concentrator current levels the main carrier loss mechanism is radiative recombination from the quantum wells. We have recently reported on evidence of hot carrier effects in the quantum well regions of GaAs based strain-balanced cells incorporating InGaAs quantum wells and GaAsP barriers [2]. This paper extends this work to a greater range of samples, and reports on a bias-dependent broadening in exciton luminescence observed in all samples at high biases. We present two possible interpretations of the data using different parts of the generalised Planck equation.