We report on the current properties of Al1−xInxN (x ≈ 0.18) layers lattice-matched (LM) to GaN and their specific use to realize nearly strain-free structures for photonic and electronic applications. Following a literature survey of the general properties of AlInN layers, structural and optical properties of thin state-of-the-art AlInN layers LM to GaN are described showing that despite improved structural properties these layers are still characterized by a typical background donor concentration of (1–5) × 1018 cm−3 and a large Stokes shift (∼800 meV) between luminescence and absorption edge. The use of these AlInN layers LM to GaN is then exemplified through the properties of GaN/AlInN multiple quantum wells (QWs) suitable for near-infrared intersubband applications. A built-in electric field of 3.64 MV cm−1 solely due to spontaneous polarization is deduced from photoluminescence measurements carried out on strain-free single QW heterostructures, a value in good agreement with that deduced from theoretical calculation. Other potentialities regarding optoelectronics are demonstrated through the successful realization of crack-free highly reflective AlInN/GaN distributed Bragg reflectors (R > 99%) and high quality factor microcavities (Q > 2800) likely to be of high interest for short wavelength vertical light emitting devices and fundamental studies on the strong coupling regime between excitons and cavity photons. In this respect, room temperature (RT) lasing of a LM AlInN/GaN vertical cavity surface emitting laser under optical pumping is reported. A description of the selective lateral oxidation of AlInN layers for current confinement in nitride-based light emitting devices and the selective chemical etching of oxidized AlInN layers is also given. Finally, the characterization of LM AlInN/GaN heterojunctions will reveal the potential of such a system for the fabrication of high electron mobility transistors through the report of a high two-dimensional electron gas sheet carrier density (ns ∼ 2.6 × 1013 cm−2) combined with a RT mobility μe ∼ 1170 cm2 V−1 s−1 and a low sheet resistance, R ∼ 210 Ω/□.

We propose to use lattice-matched AlInN/GaN to replace the Al(Ga)N/GaN material system for III-nitride Bragg reflectors, despite the poor material quality of AlInN reported until very recently. We report an improvement of AlInN material that allowed for successful fabrication of a microcavity light emitting diode, a distributed Bragg reflector with 99.4% reflectivity and microcavities with a quality factor over 800. These results establish state-of-the-art values for III-nitrides, and announce the future importance of AlInN in GaN-based optoelectronics.

We report the growth over 2 in. sapphire substrates of crack-free fully epitaxial nitride-based microcavities using two highly reflective lattice-matched AlInN∕GaN distributed Bragg reflectors (DBRs). The optical cavity is formed by an empty 3λ∕2 GaN cavity surrounded by AlInN∕GaN DBRs with reflectivities close to 99%. Reflectivity and transmission measurements were carried out on these structures, which exhibit a stopband of 28 nm. The cavity mode is clearly resolved with a linewidth of 2.3 nm. These results demonstrate that the AlInN∕GaN system is very promising for the achievement of strong light–matter interaction and the fabrication of nitride-based vertical cavity surface emitting lasers.

We report on the progress in the growth of highly reflective AlInN–GaN distributed Bragg reflectors deposited by metalorganic vapor phase epitaxy. Al1−xInxN layers with an In content around x∼0.17 are lattice-matched to GaN, thus avoiding strain-related issues in the mirror while keeping a high refractive index contrast of about 7%. Consequently, a reflectivity value as high as 99.4% at 450nm was achieved with a 40-pair crack-free distributed Bragg reflector. We measured an average absorption coefficient α[cm−1] in the AlInN–GaN Bragg reflectors of 43±14cm−1 at 450nm and 75±19cm−1 at 400nm. Application to blue optoelectronics is demonstrated through the growth of an InGaN–GaN microcavity light emitting diode including a 12-pair Al0.82In0.18N–GaN distributed Bragg reflector as bottom mirror. The device exhibits clear microcavity effects, improved directionality in the radiation pattern and an optical output power of 1.7mW together with a 2.6% external quantum efficiency at 20mA.

The growth of highly-reflective nitride-based distributed Bragg reflectors (DBRs) and their use in vertical cavity structures is reviewed. We discuss the various nitride material systems employed to design Bragg mirrors and microcavities, namely the Alx(Ga)1-xN/(Al)yGa1-yN and the lattice-matched Al1-xInxN/GaN (xIn∼18%)-based systems. An emphasis on particular issues such as strain management, internal absorption, alloy morphology and contribution of leaky modes is carried out. Specific properties of the poorly known AlInN alloy such as the bandgap variation with In content close to lattice-matched conditions to GaN are reported. The superior optical quality of the lattice-matched AlInN/GaN system for the realization of nitride-based DBRs is demonstrated. The properties of nitride-based vertical cavity devices are also described. Forthcoming challenges such as the realization of electrically pumped vertical cavity surface emitting lasers and strongly coupled quantum microcavities are discussed as well, and in particular critical issues such as vertical current injection.