The Photoelectric Property Study And Design Of Nitride Semiconductor Quantum Dots

The groupⅢnitride semiconductor compounds have now shown their extraordinary capacity for emitting light from the green to the ultraviolet (UV) spectral range. Semiconductor quantum dots (QD's) have been of major interest in recent years. This has largely been stimulated by progress in QD growth technology, whereby self-organized, relatively uniform, dot layers can be achieved using the Stranski-Krastanow growth mode.ⅢNitride Semiconductor QD's are of interest both from a fundamental physics perspective, enabling the study of zero-dimensional objects analogous to artificial atoms, and also because of potential device applications, particularly in the field of optoelectronics.Because of the rapid progress in QD growth technology, the theoretical study of self-organized QD's is now of major interest, both to interpret existing data, and also to guide future developments.We outline a selfconsistent theory model, including the calculation of strain and charge density, the theory of electron states in the framework of effective mass approximation (EMA), the formula of absorption coefficient of the intersubband transition. We develop an effective method using the finite element method (FEM). The discretized functional integrals are used in a variational approach , the finite element formulation allows us to evaluate functional derivatives needed to linearize the differential functions in a natural manner.We investigate the strained fields and piezoelectric effect in nitride GaN/AlN quantum dots (QDs). The strain distribution in QD structure of wurtzite(WZ) crystal symmetry is included. The QD electronic states and wave functions are calculated using the finite element method in the framework of effective mass approximation. Effects of spontaneous and piezoelectric polarization are taken into account in the calculation. It is showed that the strain field and piezoelectric potential influenced the distribution of charges. The strain dependent on deformation potential and the piezoelectric potential change the electronic sublevels and split the degenerate states. It is also shown that in an appropriate scope, the intersubband transition from the ground state to first excited state (E1→E2) has the strong oscillator strength, and these theoretical results are dependent on QD sizes. Some of them make the GaN/AlN QDs interesting candidates for...