**2. Model details**

In this section, we will develop the model, starting with the QWSC, whose structure is shown in figure 1. The make use of the common assumptions of homogeneous composition in the doped and intrinsic layers, the depletion approximation in the space-charge region, and total photogenerated carrier collection, assuming an equal carrier temperature in all regions. Transport and Poisson equations were used to compute the quantum efficiency in the charge-neutral layers while the quantum efficiency of the intrinsic region is determined taking into account the absorption coefficient of the nanostructure involved. The overall photocurrent is simply expressed in terms of superposition, adding photocurrent, obtained form the calculated quantum efficiency, to the dark current in order to find out the illuminated current-voltage characteristic.
