Growth of InN and In-rich Group III-nitride alloys in cubic phase
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In the past, wide-band-gap GaN and Ga-rich InGaN alloys, in their hexagonal phase have been extensively studied, but much less effort has been devoted to the study of InN and In-rich InGaN alloys grown in the cubic phase. Major advances at the present time derive from the much improved quality of InN films grown using molecular beam epitaxy. Recent results for the bandgap of InN, revised its value from 1.9 eV to a much smaller value of 0.64 eV and 0.60 eV, for the hexagonal and cubic phases, respectively. This finding triggered a worldwide research effort into the area of narrow-band-gap group-III nitrides. The small value of the InNbandgap provides a basis for a consistent description of the electronic structure of InGaN and InAlN alloys with all compositions. It extends the fundamental bandgap of the group III-nitride alloy system over a wider spectral region, ranging from the near infrared at 2 μm, 0.60 eV for cubic InN to the ultraviolet at 0.36 μm, 3.4 eV, for GaN. Optical studies on InN reveal a large Burstein-Moss shift of the absorption edge with increasing electron concentration n. Fundamental studies of the energy levels of defects in InN and of electron transport are also reviewed. Thecontinuous variations of bandgap energies from the near infrared to the near ultraviolet provide the possibility of newapplications for group-III nitrides. In this article we present a detailed review of the physicalproperties of InN and their growth by molecular beam epitaxy and related group III-nitride semiconductors. An advance in characterization and understanding of cubic InN is presented. ©2012 Nova Science Publishers, Inc.