Indium Gallium Nitride/Gallium Nitride (InGaN/GaN) Nanorods Superlattice (SL)

The growth condition, electrical, and optical properties of GaN nanorods grown on Si111 substrates are investigated. The GaN nanorods were grown with a different growth time by using rf-plasma assisted molecular-beam epitaxy. It is clearly demonstrated that the critical diameter for defects-free GaN nanorods is determined to be below 140 nm under the N-rich condition. Magnesium-doped GaN nanorods were also grown with the same growth condition. Two emission lines corresponding blue emission at about 3.26 and 3.18 eV were observed. These peaks are attributed to conduction band-to-shallow acceptor transitions and to defects associated with columnsubstrate interface-shallow Mg acceptor complexes, respectively. Finally, they have fabricated a p-n junction diode using the GaN nanorod. The GaN nanorod was patterned on SiO2 substrate by using E-beam lithography. The current-voltage curve exhibits strong temperature dependence, suggesting that thermionic emission over a barrier dominates. This barrier is most likely corresponding to emission from a deep level in the band. The deep level appears to be an electron trap at Ec-0.40 eV below the conduction band with a capture cross section of 2.22 61620 10-16 cm2 near the depletion region of the p-n junction.