PROCEEDINGS ARTICLE | March 11, 2011
Proc. SPIE. 7940, Oxide-based Materials and Devices II
KEYWORDS: Ellipsometry, Refractive index, Data modeling, Ultraviolet radiation, Silicon, Reflectivity, Gallium nitride, Aluminum nitride, Boron, Zinc oxide
In the last decades, development of the (Al,Ga,In)N materials has led to new generations of opto- and micro-electronic
devices. More recently, novel B(Al,Ga,In)N alloys have been proposed for optical applications in the UV range. Since
material containing boron possesses unique properties, the B(Al,Ga,In)N materials system is expected to permit the
design of improved and/or novel devices. To evaluate this potential, an improved knowledge of the physical properties of
these new materials will be required, however.
In this work, investigation of optical, structural, and compositional properties of low-boron content BGaN and BAlN
ternary and BInGaN quaternary materials grown through Metalorganic Vapor Phase Epitaxy (MOVPE) are presented. It
is shown that inclusion of a small amount of boron strongly affects the optical properties allowing the fabrication of
BGaN-based Distributed Bragg Reflectors (DBRs) or Distributed Bragg Confinement layers (DBCs) with large
refractive index contrast. Indeed, 1% of boron in BGaN/GaN multilayer structures gives a refractive index contrast of
more than 0.1, which is equivalent to that of AlGaN/GaN containing 22% aluminum. The potential of boron-based
material technology is illustrated for visible range solar cells applications through the example of BInGaN with good
crystalline quality grown on ZnO buffered silicon substrates. It was found that through boron introduction, reduced
lattice mismatch, and thus reduced tensile strain, could be obtained for high In contents.
