Effect of polarization on two-dimensional carrier distribution in nitride quantum wells

• Published in: Physica. E, Low-dimensional systems & nanostructures Low-dimensional systems & nanostructures, 2005-01, Vol.25 (4), p.449-455
• Main Authors: Lahiri, Bidisha, Datta, Reshmee, Kundu, Sudakshina
• Format: Article
• Language: English
• Subjects: Compound semiconductor (nitrides); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Modeling; Nanostructure; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Self-consistent calculation
• ISSN: 1386-9477; 1873-1759
• DOI: 10.1016/j.physe.2004.07.014

Wide band-gap group-III nitrides are important for the design of optical devices in the blue and blue–green region. Owing to their wurtzite structure, these materials have a strong inherent polarization field that affects carrier distribution, exciton stability and hence influences the optical properties of the devices. So far, carriers have been assumed to have a sheet-like character. In this paper a non sheet-like distribution function for these quasi two-dimensional carriers is proposed that incorporates the effect of the polarization field. Here GaN/InGaN/GaN and AlGaN/GaN/AlGaN quantum wells have been studied. The polarization field causes the electron and hole wave functions to separate out, thus causing decrease of emission strength and strong reduction of exciton binding energy. This treatment explains well the qualitative nature of carrier distribution in the well. The polarization field changes with GaN mole fraction present in the tertiary nitride layer. The effect of mole fraction on carrier distribution has also been studied. It is found that, inside the well, the hole distribution changes a little more with change in mole fraction than the electron distribution, but for all practical purposes the net change in the distribution pattern is negligible.