We investigate theoretically the influence of indium surface segregation in InGaN/GaN single quantum wells
on its optical properties. Obtained results show that the influence of the surface segregation on the dipole
matrix element is not equal for all optical transition. This effect results from the joint action of the piezoelectric
polarization and indium surface segregation which change selection rules. Quantum well structures having
different indium amount are analyzed and found that the influence of the indium surface segregation on absorption
spectra is more pronounced in quantum well structures with high indium amount.
In this work we investigate the influence of extractor design and temperature on transport properties of quantum
cascade detector. For this purpose we realize numerical calculation of electron lifetimes considering electronphonon
and electron impurities scattering. Electron-phonon interactions are treated using Fermi Golden Rule
which allows to calculate lifetime of carriers with temperature and structure design taking into account. Transport
characteristics of the quantum cascade detectors have been computed using density matrix theory. As a result, we
have obtained the system of ordinary differential equations describing dynamics of electron distribution functions
and intersubband correlations. Managing carrier lifetime in quantum wells gives us possibility to control quantum
efficiency and response.
In the paper, the problem of the effective enhancement of electron capture efficiency has been considered for MQW structures. Different approaches to the problem are used. The most effective one is based on embedding of additional layers in SQH region. We have investigated the influence of such layers on two types of carriers' capture. The first one is the capture of bound carriers from reservoir states in SQH region and the second one is the capture of free carriers from quasi-continuum states. As a result, we have obtained up to tenfold increase of electron capture efficiency.