One embodiment of the present invention provides a method for fabricating a group III-V p-type nitride structure. The method comprises growing a first layer of p-type group III-V material with a first acceptor density in a first growing environment. The method further comprises growing a second layer of p-type group III-V material, which is thicker than the first layer and which has a second acceptor density, on top of the first layer in a second growing environment. In addition, the method comprises growing a third layer of p-type group III-V material, which is thinner than the second layer and which has a third acceptor density, on top of the second layer in a third growing environment.