Effect of Ge-doping on the short-wave, mid- and far-infrared intersubband transitions in GaN/AlGaN heterostructures
arXiv:1903.09375 · doi:10.1088/1361-6641/aa919c
Abstract
This paper assesses the effects of Ge-doping on the structural and optical (band-to-band and intersubband (ISB)) properties of GaN/AlGaN multi-quantum wells (QWs) designed to display ISB absorption in the short-wave, mid- and far-infrared ranges (SWIR, MIR, and FIR, respectively). The standard c-plane crystallographic orientation is considered for wells absorbing in the SWIR and MIR spectral regions, whereas the FIR structures are grown along the nonpolar m-axis. In all cases, we compare the characteristics of Ge-doped and Si-doped samples with the same design and various doping levels. The use of Ge appears to improve the mosaicity of the highly lattice-mismatched GaN/AlN heterostructures. However, when reducing the lattice mismatch, the mosaicity is rather determined by the substrate and does not show any dependence on the dopant nature or concentration. From the optical point of view, by increasing the dopant density, we observe a blueshift of the photoluminescence in polar samples due to the screening of the internal electric field by free carriers. In the ISB absorption, on the other hand, there is a systematic improvement of the linewidth when using Ge as a dopant for high doping levels, whatever the spectral region under consideration (i.e. different QW size, barrier composition and crystallographic orientation).
arXiv commentThis is the accepted manuscript version of an article that appeared in Semiconductor Science and Technology. The CC BY-NC-ND 3.0 license applies, see https://creativecommons.org/licences/by-nc-nd/3.0
References in corpus (6)
- Terahertz intersubband absorption in non-polar m-plane AlGaN/GaN quantum wells
- Ge doping of GaN beyond the Mott transition
- Atomically thin spherical shell-shaped superscatterers based on Bohr model
- Effect of doping on the intersubband absorption in Si- and Ge-doped GaN/AlN heterostructures
- Intersubband transitions in nonpolar GaN/Al(Ga)N heterostructures in the short and mid-wavelength infrared regions
- Temperature stability of intersubband transitions in AlN/GaN quantum wells