High structural quality InN/In0.75Ga0.25N multiple quantum wells grown by molecular beam epitaxy

InN/In0.75Ga0.25N multiple quantum wells (MQWs) were grown by rf plasma-assisted molecular beam epitaxy. The high-resolution transmission electron microscope and x-ray diffraction measurements showed evidence of growth of atomically smooth and sharp interface and good periodicity. Room-temperature photoluminescence emissions from InN quantum wells were observed at the wavelength range from 1.59 to 1.95 mu m by changing the well thickness. The unstrained valence band offset of InN/GaN was estimated to be Delta E-v=0.9 eV by comparing the experimental transition wavelengths of the MQWs and a theoretical calculation considering strain effects and built-in, mainly piezoelectric, fields. (c) 2006 American Institute of Physics.