Growth of N-doped p-type ZnO films using ammonia as dopant source gas

摘要

The wide direct-band gap semiconductor material, ZnO, has attracted considerable attention for such applications as ultraviolet (UV) and blue light-emitting diodes (LED) and laser diodes (LD) [1,2]. ZnO has not only the same crystal structure as GaN, but also a larger exciton binding energy of 60 meV, which is 2.4 times that of GaN (21 meV). So ZnO films show very strong spontaneous and stimulated emissions by excitons even at room temperature [3]. This indicates that ZnO should be a potential material to realize for the next generation UV and blue semiconductor opto-electronic devices. The application of ZnO films, however, has been limited because of the quality of the materials. A main reason is probably that no high quality p-type ZnO has been available by now since ZnO is natively a stongly n-type semiconductor.