Manipulation of Room Temperature Ferromagnetic behavior of GaMnN Epilayers

Abstract

We report on metal organic chemical vapor deposition growth of GaMnN/p-GaN/n-GaN multilayer structures and manipulation of room temperature (RT) ferromagnetism (FM) in a GaMnN layer. The GaMnN layer was grown on top of a n-GaN substrate and found to be almost always paramagnetic. However, when grown on a p-type GaN layer, a strong saturation magnetization (M s ) was observed. M s was almost doubled after annealing demonstrating that the FM observed in GaMnN film is carrier-mediated. To control the hole concentration of the p-GaN layer by depletion, GaMnN/p-GaN/n-GaN multilayer structures of different p-GaN thickness (X p ) were grown on sapphire substrates. We have demonstrated that the FM depends on the X p and the applied bias to the GaN p-n junction. The FM of these multilayer is independent on the top GaMnN layer thickness (t GaMnN ) for t GaMnN >200 nm and decreases for t GaMnN < 200 nm. Thus the room temperature FM of GaMnN i-p-n structure can also be controlled by changing X p and t GaMnN in the GaMnN i-p-n structures.