The interfacial features in photoluminescence of In_0.52Al_0.48As/InP distinguished with selective excitation

The photoluminescence experiment was performed at 77 K on two types of heterostructures of In0.52Al0.48As/InP grown by molecular beam epitaxy. One type has the so-called direct interface formed with In0.52Al0.48As grown on the InP (100) substrate, and another is a double heterostructure type, i.e., InP/In0.52Al0.48As/InP, including the inverse interface formed with the InP cap. The thickness of both the as-grown InAlAs and InP layers is 2 mu m. Under the excitation of 852 nm semiconductor laser, a single peak at 1.198 eV (P0) was observed for the direct interface whereas the inverse interface showed two peaks at 1.240 eV (P1) and 1.117 eV (P2). However, P2 manifests differently from P1 with two interesting features. First, it disappears when the excitation was replaced with the 532 nm laser. Second, when the cap layer of InP/In0.52Al0.48As/InP is thinned to 200 nm, P2 displays a large blueshift effect with the increase in laser intensity, but the extent of blueshift drops when the excitation is increased further into a higher power range. The phenomenon of P2 was attributed to the interface excitation-induced interplay between the luminescence with a carrier localization effect and that caused by the recombination of 2-dimensional electrons with the light-injected holes in the potential well at the interface.