Chen, HuiGu, ShulinLiu, JiagaoYe, JiandongTang, KunZhu, ShunmingZheng, Youdou2015-12-112015-12-110003-6951http://hdl.handle.net/1885/70371Radiative 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 100 K 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.Research is supported by the State Key Program for Basic Research of China under Grant No. 2011CB302003 and National Natural Science Foundation of China (Nos. 61025020 and 60990312).http://www.sherpa.ac.uk/romeo/issn/0003-6951..."Publishers version/PDF may be used on author's personal website, institutional website or institutional repository" from SHERPA/RoMEO site (as at 11/12/15). Copyright 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters and may be found at https://doi.org/10.1063/1.3662964Keywords: Depth profile distributions; Donor-bound exciton; Flat band; Hall effect measurement; Hetero interfaces; Indirect transition; Photoexcited holes; Radiative recombination; Residual strains; Two-dimensional electron gas (2DEG); ZnMgO; ZnO; Crystals; Gas emi2011-11-2210.1063/1.36629642016-02-24