Two-dimensional electron gas related emissions in ZnMgO/ZnO heterostructures

Radiative recombination of two-dimensional electron gas (2DEG), induced by polarization and validated by Hall effect measurements, is investigated in ZnMgO/ZnO heterostructures grown by metal-organic chemical vapor deposition. The Mg composition, the depth profile distribution of Mg, the residual strain in ZnMgO caplayer, and the thickness of caplayer all significantly influence the 2DEG-related transitions in ZnMgO/ZnO heterostructures. Below or above ZnO donor bound exciton, three additional broad emissions persisting up to 100K are assigned to the spatially indirect transitions from 2DEG electrons to the photoexcited holes towards the ZnO flat-band region or remaining at the heterointerface. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3662964]