Emission of quantum dots (QDs) and isoelectronic bound excitons (IBEs) from submonolayer ZnTe on ZnSe and dependence on thickness of ZnTe

Zn-Se-Te systems have been of great interest for both lighting applications and their unique optical properties. It is known that the PL of the dilute alloys [1] or quantum wells [2] is usually due to IBEs. ZnTe/ZnSe QDs have been grwon with full monolayer coverage of ZnTe on ZnSe using Volmer-Weber growth [3]. We have shown [4] the existence of type-II QDs in ZnSeTe multilayers grown by migration enhanced epitaxy with sub-monolayer quantities of ZnTe. The multilayers were grown using three Zn-Te deposition cycles sandwiched between nominally pure ZnSe barriers. Here, we report ZnTe/ZnSe QDs grown by a similar method, but with only one ZnTe deposition cycle. It is interesting that at T = 10K the PL emission related to these QDs does not shift upon varying the excitation intensity, and attributed to IBEs; however, a large energy shift is observed at T = 80K, suggesting formation of type-II QDs. The presence of type-II QDs is also supported by magneto-PL measurements. \newline [1] Permogorov and Reznitsky, J. Lumin. \textbf{52}, 201 (1992). \newline [2] Suzuki et al., J. Crystal Growth \textbf{184/185}, 882 (1998). \newline [3] Yang et al., JAP \textbf{97}, 033514 (2005). \newline [4] Kuskovsky, et al., Phys. Stat. Sol. (b) \textbf{241}, 527 (2004); Gu et al., Phys. Rev. B \textbf{71}, 045340 (2005).