Klymenko M. Optical spectral characteristics of InGaN/GaN semiconductor heterostructures with quantum wells

Thesis for a Doctor Philosophy degree (Ph.D.) in physical-mathematical sciences by according to scientific specialty 10.04.05 optics, laser physics. V.N. Karazin Kharkiv national university, Kharkiv, 2011. In the thesis, theoretical investigation of the optical response has been carried out for the InGaN/GaN semiconductor heterostructure with the quantum well. Joint action of piezoelectric polarization, charge screening and surface segregation on the potential relief, dipole matrix element for optical interband transitions, band structure of energy spectra, absorption and optical spectra has been investigated including into consideration many-body effects. As a result of investigations, it has been determined that the indium surface segregation leads to changes in band structure that causes blue shifts of absorption red edge. Magnitude of the spectral shift is increased with indium molar fraction in the quantum-well layer. Many-body effects leads to red-shift of spectra due to exchange interactions. The piezoelectric polarization causes decreasing of exciton resonances and lowering of absorption and gain coefficients. Based on obtained results, the conditions of minimal influence of the indium surface segregation have been formulated.