Structure of Zn–Se–Te system with submonolayer insertion of ZnTe grown by migration enhanced epitaxy.

We here report results of high resolution x-ray diffraction, x-ray reflectivity (XRR), as well as optical absorption and reflection measurements on ZnSe samples grown by molecular beam epitaxy, with insertion of planar (δ-) regions of both N as an acceptor dopant and Te as a “co-dopant” to facilitate a p-type doping. We note that to enhance the surface diffusion of Te, migration enhanced epitaxy was adopted in the growth of the “δ-layers;” i.e., Te is deposited in the absence of Zn flux. Structural parameters were extracted by simulating the experimental x-ray diffraction curves using a dynamical model. The results show that only the “δ-layers” (with submonolayer thickness) are rich in ZnTe, while the nominally undoped “spacers” have only a low Te concentration. Moreover, the morphology of the surface and interfaces are studied by XRR. Furthermore, the optical absorption and reflection results show that our samples largely preserve the optical properties of the host material (ZnSe). We note that our results, in particular those on the Te concentration, explain the observed good p-type doping of such samples. [ABSTRACT FROM AUTHOR]