Comparison of the saturated current in normal and inverted modulation-doped In0.53Ga0.47As/InP structures

We measured the saturated current in both normal (doping layer on top) and inverted (doping layer on bottom) structures of modulation-doped In0.53Ga0.47As/InP. In the inverted structure, we find a saturated current consistent with the low-field carrier density and the bulk electron saturated velocity; but for the normal structure the saturated current is significantly lower than expected. Measurements indicate that this low saturation current is due to a loss of carriers at high fields.