MBE growth and applications of cubic AlN/GaN quantum wells

Abstract

Molecular beam epitaxy (MBE) of cubic group III-nitrides is a direct way to eliminate polarization effects which inherently limit the performance of optoelectronic devices containing quantum well or quantum dot active regions. In this contribution, the latest achievement in the MBE of phase-pure cubic GaN, AlN, and AlN/GaN quantum wells will be reviewed. The structural, optical, and electrical properties of state of the art cubic nitrides and AlGaN/GaN will be presented. We show that no polarization field exists in cubic nitrides and demonstrate intersubband absorption at 1.55 mm in cubic AlN/ GaN superlattices. Comparing the experimental results with simulations based on an effective-mass model the GaN/AlN conduction-band offset is demonstrated to be higher than 1.2 eV. The best fit with the experimental data is achieved for a conduction-band offset of 1.4 eV. Further the progress toward the fabrication of cubic GaN/AlGaN superlattices for terahertz applications will be discussed and our first experiments on cubic AlN/GaN resonant tunneling devices will be reported.

Electron-electron and electron-phonon correlation effects on the finite-temperature electronic and optical properties of zinc-blende GaN

“…In last few years zb-GaN with high phase-purity and crystalline quality has been fabricated as a nearly strainfree epitaxial layer on 3C-SiC(001)/Si pseudo substrates by plasma-assisted molecular beam epitaxy 6,[9][10][11] . This experimental achievement boosted the interest on fundamental optical properties as photoluminescence, photoreflectance and ellipsometry with particular attention on their temperature dependence.…”

Understanding band alignments in semiconductor heterostructures: Composition dependence and type-I–type-II transition of natural band offsets in nonpolar zinc-blendeAlxGa1−xN/AlyLandmann1, Rauls2, Schmidt3 2017Phys. Rev. B19060View full textAdd to dashboardCite

“…The group-III nitride-based design of novel functional materials for optoelectronic devices as diodes, transistors, photodetectors, and sensors, and in particular solar cells, commonly involves the formation of small-scale multicomponent semiconductor complexes to exploit the material system's full technological potential beyond simple bulk-band gap engineering. Group-III nitride materials, especially, show beneficial material properties for utilization in intersubband devices working at both the near-infrared telecommunication wavelength regime as well as the far-infrared THz wavelength edge by exploiting electronic transitions between nanostructureconfined electronic states in single or multiple quantum well as well as quantum-dot heterostructures [26][27][28][29]. In any semiconductor heterostructure the alignment of electronic bands at built-in heterojunctions, by means of valence-band edge and conduction-band edge offsets, is crucial for the electron-transport dynamics and charge carrier confinement.…”

“…Within the present study, we will focus on the less common nonpolar zincblende phases of Al x Ga 1−x N alloys, whose centrosymmetric crystal structure effectively prevents the technologically limiting emergence of polarization fields [6,27,50]. A key characteristic of the electronic structure and, thus, related physical properties of the nonpolar zb-Al x Ga 1−x N semiconductors, is the presence of a direct-indirect band-gap crossing around x ≈ 0.65 in the fundamental alloy-energy gap [51].…”

Correlation of the Carrier Decay Time and Barrier Thickness for Asymmetric Cubic GaN/Al0.64Ga0.36N Double Quantum Wells

“…Another method is the growth of the metastable cubic phase along (001) on 3C‐SiC substrate. This leads to a significantly suppression of the mentioned effects along the growth axis …”