Chapter 6 - Nonpolar Cubic III-nitrides: From the Basics of Growth to Device Applications

Abstract

The molecular beam epitaxy (MBE) of cubic group III-nitrides is a direct way to eliminate polarization effects, which may limit the performance of optoelectronic devices containing quantum well or quantum dot (QD) active regions. In this paper, recent progress with the MBE of phase-pure cubic GaN, AlN, and their alloys is reviewed. Reflection high-energy electron diffraction has extensively been used to adjust stoichiometric growth conditions allowing severe reduction of the surface roughness of layers and optimization of the hetero-interfaces and structural quality of multilayer stacks. The absence of polarization fields in cubic nitride nanostructures has been demonstrated. We summarize the performance of device structures taking advantage of this property, like heterojunction field-effect transistors with both normally on and normally off characteristics, as well as devices for intersubband absorption in the spectral range between 1.55μm and the terahertz region and single photon emission of cubic GaN QDs.