Positive and negative persistent photoconductivity in a two-side-doped In0.53Ga0.47As/In0.52Al0.48As quantum well

We present detailed studies of the persistent photoconductivity effect in I n0.53Ga0.47As/In0.52Al0.48As quantum well, including wavelength, temperatur e, and time dependencies. We found conclusive results that show competition between the positive and negative persistent photoconductivity effects. We suggest that a complete understanding of the decay and buildup kinetics in the entire temperature region must incorporate both the positive and negat ive effects. We conclude that the major positive effect is due to the band- to-band electron-hole generation in the well layer followed by the spatial charge separation and the negative effect is related to the pumping of the two-dimensional electrons into the doped barrier layer followed by the decr ease of mobility. [S0163-1829(99)03443-8].