Rare-earth in III-V semiconductors and related alloys: point defects and nanoparticles

The incorporation of rare-earth elements into III-V semiconductors has been widely studied for their unique optical, electrical, and thermoelectric properties. Depending on growth conditions, rare-earth impurities can either remain isolated or form mono-pnictide (RE-V) nanoparticles embedded in III-V matrices. For instance, Er impurities in GaAs yield a sharp, temperature-independent emission peak at 1.55 μm, matching the lowest attenuation wavelength of silica optical fibers. ErAs nanoparticles in GaAs, on the other hand, reduce carrier lifetime and increase phonon scattering, decreasing thermal conductivity and enhancing electrical conduction via electron filtering. Using first-principles calculations, we investigate the structural and electronic properties of ErAs nanoparticles in AlAs, GaAs, InAs, and their alloys. We also examine the incorporation of La, Pr, Gd, Tb, Er, and Lu into interstitial and substitutional sites in zinc blende lattices, exploring various charge states. For nanocomposites, spherical ErAs nanoparticles are found to be the most energetically favorable, with larger diameters leading to Fermi level pinning near mid-gap in GaAs and AlAs, and resonant with the conduction band in InAs. Our results demonstrate that the Fermi level is pinned on an absolute energy scale when considering band alignments at AlAs/GaAs/InAs interfaces, providing key insights into the design of these nanocomposites [1]. Additionally, we analyze the stability of isolated rare-earth impurities in III-Vs, offering insights into their potential for enhancing semiconductor device performance.

[1] R. Hu, D.Q. Ho, D.Q. To, G.W. Bryant, A. Janotti, Nano Lett. 24, 15, 4376 (2024).