Electrical characterization of p-type N-polar and Ga-polar GaN grown by metalorganic chemical vapor deposition

We report on Mg- doped N- polar and Ga- polar GaN films grown by metal organic chemical vapor deposition (MOCVD). The bis- cyclopentadienyl magnesium flow was varied from 64 to 640 nmol/ min, for N- polar and Ga- polar samples, while other growth conditions were held constant. The sample surfaces were characterized by atomic force microscopy. Electrical measurements were made to determine the resistivity, specific contact resistance, carrier concentrations, mobilities, and activation energies. Finally, current- voltage measurements were used to characterize the properties of N- polar p- n diodes. Comparisons between both polarities demonstrate that p- type N- polar GaN can be grown by MOCVD with comparable properties to Ga- polar GaN. (C) 2007 American Institute of Physics.