Author:
Stanojević Novak,Demić Aleksandar,Vuković Nikola,Dean Paul,Ikonić Zoran,Indjin Dragan,Radovanović Jelena
Abstract
AbstractIn this work, we investigate the effects of n and p-type background doping, interface composition diffusion (interdiffusion) of the barrier material and layer thickness variation during molecular beam epitaxy (MBE) growth on transport characteristics of terahertz-frequency quantum cascade lasers (THz QCLs). We analysed four exemplary structures: a bound-to-continuum design, hybrid design, LO-phonon design and a two-well high-temperature performance LO-phonon design. The exemplary bound-to-continuum design has shown to be the most sensitive to the background doping as it stops lasing for concentrations around $$1.0\cdot 10^{15}$$
1.0
·
10
15
–$$2.0\cdot 10^{15}$$
2.0
·
10
15
cm$$^{-3}$$
-
3
. The LO-phonon design is the most sensitive to growth fluctuations during MBE and this is critical for novel LO-phonon structures optimised for high-temperature performance. We predict that interdiffusion mostly affects current density for designs with narrow barrier layers and higher $$\textrm{Al}$$
Al
composition. We show that layer thickness variation leads to significant changes in material gain and current density, and in some cases to the growth of nonfunctional devices. These effects serve as a beacon of fundamental calibration steps required for successful realisation of THz QCLs.
Publisher
Springer Science and Business Media LLC