Evidence for a type I to type II transition in (Ga,In)(N,As)/Ga(N,As) quantum well structures

We investigated the interband transitions of Ga0.7In0.3N0.005As0.995/GaNxAs1−x and Ga0.77In0.23As/GaNxAs1−x quantum wells with x of 0–3% by modulation spectroscopy. When N is incorporated into the barrier a change of the band alignment must occur due to the large red-shift of the Ga(N,As) band gap with increasing N. Therefore, a variation of x leads to a considerable change of the carrier confinement of holes and, in particular, of electrons. At x≈1% in the barrier a band alignment transition from type I to type II can be observed for the N-free wells. For N-containing wells, the band alignment changes at x≈3%.