Optical properties of undoped and modulation-doped AlxGa1-xN/GaN heterostructures grown by metalorganic chemical vapor deposition

The radiative recombination of carriers in a two-dimensional electron gas ( 2DEG) in undoped and modulation-doped AlxGa1-xN/GaN heterostructures grown by metalorganic chemical vapor deposition is investigated at low temperatur e using photoluminescence measurements. Temperature-dependent Hall effect a nd Shubnikov-de Haas measurements, verify the formation of a high-quality 2 DEG. Radiative recombination is observed between the 2DEC in quantum states at the hetero-interface and the holes in the flat-band region or bound to residual accepters both in undoped and top AlGaN layer is removed by reacti ve ion etching. In addition, the effect of the growth interruption time, la ser excitation intensity, and doping conditions upon the photoluminescence is also described. (C) 2000 Elsevier Science B.V. All rights reserved.