The effect of InxGa1−xN back-barriers on the dislocation densities in Al0.31Ga0.69N/AlN/GaN/InxGa1−xN/GaN heterostructures (0.05 ≤ x ≤ 0.14)

Al0.31Ga0.69N/AlN/GaN/InxGa1−xN/GaN heterostructures grown with the metal-organic chemical vapor deposition (MOCVD) technique with different InxGa1−xN back-barriers with In mole fractions of 0.05 ≤ x ≤ 0.14 were investigated by using XRD measurements. Screw, edge, and total dislocations, In mole fraction of back-barriers, Al mole fraction, and the thicknesses of front-barriers and lattice parameters were calculated. Mixed state dislocations with both edge and screw type dislocations were observed. The effects of the In mole fraction difference in the back-barrier and the effect of the thickness of front-barrier on crystal quality are discussed. With the increasing In mole fraction, an increasing dislocation trend is observed that may be due to the growth temperature difference between ultrathin InxGa1−xN back-barrier and the surrounding layers.

► Determining quality of InxGa1−xN layers are important.
► Samples' growth, ultrathin layers were grown at lower temperatures instead of higher temperature grown surrounding layers.
► Edge and screw dislocations seem to increase linearly.
► By increasing In mole fraction, temperature difference becomes more effective.
► By increasing In mole fraction, increasing dislocation trend was observed.