Relationship of background carrier concentration and defects in GaN grown by metalorganic vapor phase epitaxy

Experimental results show that the background carrier concentrations in GaN films grown by metalorganic vapor phase epitaxy are related to defects. A thermal equilibrium method was used to calculate the background carrier concentration related to intrinsic defects in an ideal GaN crystal. The results show that the N vacancy concentration does not exceed 2 × 10¹⁷ cm^-3 in GaN grown at temperatures ranging from 800 to 1500 K. It can be concluded that the N vacancy is one of the major sources of carriers when the carrier concentration n<2 × 10¹⁷ cm^-3, but the main sources should be other defects when n>2 × 10¹⁷ cm^-3; this conclusion may lead to ways for further improving the quality of GaN films.