Considerable attention has been paid to ZnO due to its wide direct band gap of 3.3 eV and large(exciton) binding energy of 60 meV at room temperature.Thus it becomes a promising material for ultraviolet light emitting diodes and lasers

transparent high power electronic devices and widely used in our community.In order to fabricate ZnO-based optoelectronic devices

both n-and p-type ZnO are needed.Undoped ZnO(exhibits) intrinsic n-type conductivity

and it is

therefore

difficult to achieve p-type ZnO because the fact that acceptors are compensated by various native donors

such as oxygen vacancies

Zn interstitial

and other(donors.) Except for the group-ⅴ dopants

Li is considered to be a shallow p-type impurity for ZnO.However

in practice it is still difficult to obtain p-type ZnO by Li dopant because Li substituting for Zn(Li

Zn

) is metastable.Thus much attention has been paid on stability researches of p-type dopant in Li doped ZnO.The first-principles calculations were carried out with a powerful package called VASP(Vienna ab initio simulation package).The wave functions are expressed by plane waves with a cutoff energy 395.99 eV.Ionic potentials are represented by ultrasoft pseudopotentials with the Perdew-Wang 1991(PW91) GGA(genera-(lized) gradient approximation) correction.And 32-atom supercells were used to perform the total energy calcu-(lation.) Further

in order to improve the stability of Li

Zn

in ZnO crystal

the geometrical and electronic structures of the different complexes of Li

Zn

with native point defects were constructed and calculated.The calculated results show that some complexes of Li

Zn

with native point defects can not only improve the stability and solubility of the defects

but also change their electronic structures.By comparing the stabilities and the related energy states of the complexes

O

Zn

-Li

Zn

complex has the lowest formation energy and also has shallow accept levels.It is suggested to be the best acceptor candidate for the p-type ZnO.But the formation of O

Zn

-Li

Zn

complex in practice is waiting for further investigations on crystal growth and device fabrication.