Intersubband transitions in InGaAsN/GaAs quantum wells.

The dependences of intersubband transitions on well width and nitrogen (N) content in n-type In_0.23Ga_0.77As_1-xN_x/GaAs quantum wells (QWs) are investigated using a ten-band k·p model. The absorption peak energy is found to increase first with the well width starting from 2 nm. It becomes insensitive from about 2.5 to 4.5 nm although the absorption intensity increases and bandwidth decreases monotonically, and then keeps decreasing with the well width beyond 4.5 nm. The peak energy is much larger than that of the N-free structure for narrower wells, but the difference decreases quickly with increasing well width. In the case of wider wells, the absorption peak energy shows relatively slow monotonic increase with increasing N content up to 3% because of the N-band and conduction-band coupling. In the nearly lattice-matched GaAsN/AlGaAs QWs the absorption peak energy shows a redshift with increasing N content from 0% to 0.4% and then increases gradually. The theoretical results are consistent with the reported experimental data. [ABSTRACT FROM AUTHOR]