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Radiative recombination of confined electrons at the MgZnO/ZnO heterojunction interface

Choi, Sumin; Rogers, David J.; Sandana, Eric V.; Bove, Philippe; Teherani, Ferechteh H.; Nenstiel, Christian; Hoffmann, Axel; McClintock, Ryan; Razeghi, Manijeh; Look, David; Gentle, Angus; Phillips, Matthew R.; Ton-That, Cuong

Inst. Festkörperphysik

We investigate the optical signature of the interface in a single MgZnO/ZnO heterojunction, which exhibits two orders of magnitude lower resistivity and 10 times higher electron mobility compared with the MgZnO/Al2O3 film grown under the same conditions. These impressive transport properties are attributed to increased mobility of electrons at the MgZnO/ZnO heterojunction interface. Depth-resolved cathodoluminescence and photoluminescence studies reveal a 3.2 eV H-band optical emission from the heterointerface, which exhibits excitonic properties and a localization energy of 19.6 meV. The emission is attributed to band-bending due to the polarization discontinuity at the interface, which leads to formation of a triangular quantum well and localized excitons by electrostatic coupling.