Impact Of Finitely Thick Barrier On Linear And Non-Linear Optical Absorption Coefficient Of GaN/Al_xGa_1-xN Sphere Quantum Dots

With the rapidly development of semi-conductor growing techniques, condensed state physical research always focuses on semi-conductor quantum dots, especially the physical properties of optical absorption like photoelectric property, transport property are originally and widely used. Based on effective-mass approximation, this thesis analyzes finitely thick barrier, impurity state electron of sphere quantum dots from 1S state to 2Po state, first-order linear and third-order nonlinear optical absorption coefficient and pressure effect. The variations of dimensions of quantum dots, finitely thick barrier and components are numerically calculated. The influence of hydrostatic pressure to linear and non-linear optical absorption is discussed. The results indicate that along with reduction of barrier thickness, the third-order absorption coefficient decreases, first-order absorption coefficient and total absorption coefficient increase. Moreover, a blue shift of absorption peak is observed. The sub-band transition, increase and blue shift of absorption peak are observed with decrease of quantum dots and increase of components. With the increase of pressure,the peak of absorption coefficient is shifted to short wave direction (blue shift). The red shift of optical absorption peak will increase along with decrease of hydrostatic pressure. Therefore, the impact of barrier thickness on impurity state absorption coefficient of sphere quantum dots can not be ignored.