Spherical Quantum Dots In The Class Of Hydrogen Donor Impurity Electronic Structure

The quantum dots(QDs) in which structure the charge carriers are confined in all three dimensions has prominent quantum effect.This effect directly affects the electron structure, transmission and optical characteristic and so on.The calculation of electron structure is a basic and important question,for electronic states are the basis of the design of various photoelectronic devices in QDs.With the progress in growth technology of QD,the theory study of electronic states is currently a subject of intense interest.In addition,in recent years,QD based on the wide-band-gapⅢ-Ⅴnitride GaN have attracted significant attention due to conspicuous device application in electrics and optoelectronics.The investigation,exploitation and application GaN QDs have been the aim of the investigator.In this article,within the framework of effective mass approximation,we have studied the electronic structure of a hydrogenic donor impurity in zinc-blende CraN/Al_xGa_1-xN spherical QD using plane wave method.The main contents are presented as following.1.The basic knowledge of QDs,the possible application and the main properties of QDs are introduced systematically.The fabricated methods and the main theoretical research methods are also introduced.2.The electronic states as functions of Al content and the radius in GaN/Al_xGa_1-xN spherical quantum dots are studied.Furthermore,the modification of energy states is calculated when the difference in effective electron masses in GaN and Al_xGa_1-xN material is considered.The results show that the difference in effective mass can not be neglected when the Al content and the radius are large.3.The factors to affect the binding energy are discussed.Numerical results show that the binding energy is highly dependent on QD size,Al content and impurity position.As show in these results,the binding energy increases until it reaches a maximum value, then decreases as the QD radius increases.As the Al content increases,the bindingenergy increases monotonically.The donor binding energy is symmetric around the centre of the QD and has a maximum value when the impurity is located at the centre of the QD.The binding energy decreases as the impurity shifts from centre to the edge of the QD4.The effect of external field on binding energy is discussed.The results indicate that the maximum of impurity binding energy is shifted from the centre of QD and the degenerating energy located for symmetrical positions with respect to the centre of QD are split in presence of the external electric field.The binding energy is more sensitive to external electric field for the large QD and lower Al content.when the magnetic field is applied to the QD,the binding energy increases as the magnetic field increases when the impurity located at the centre of QD.As the external electric field,the binding energy is sensitive to magnetic field for the large QD.When considering simultaneous effect of electric and magnetic field on the binding energy,an increase in the electric field strength or the decreases in the radius leads to a decrease of the maxima of binding energy with an increase in magnetic field.