Impact of aluminum concentration and magnesium doping on the effect of electron injection in

摘要

The impact of electron injection on the minority carrier diffusion length was studied at various temperatures in p-type Mg-doped GaN, Al_(0.2)Ga_(0.8)N, and Al_(0.2)Ga_(0.8)N/GaN superlattices, which were homogeneously and modulation (barrier only) doped. The activation energies for the electron injection-induced effect were found to be in the range from 190 to 260meV, which is close to the thermal ionization energy of the Mg-acceptor. The obtained results are in agreement with the previously proposed model of minority carrier transport enhancement due to charging of Mg-centers in p-(Al)GaN. The activation energy of the electron injection effect observed in Al_(0.2)Ga_(0.8)N is consistent with the deepening of Mg-acceptor level due to the incorporation of Al into GaN lattice. The activation energy in the Al_(0.2)Ga_(0.8)N/GaN superlattice, homogeneously doped with Mg, indicates that the main contribution to the effect comes from the capture of injected electrons by the wells.