The effect of In _xGa _(1-x)N back-barriers on the dislocation densities in Al _(0.31)Ga _(0.69)N/AlN/GaN/In _xGa _(1-x)N/GaN heterostructures (0.05 ≤ x ≤ 0.14)

摘要

Al _(0.31)Ga _(0.69)N/AlN/GaN/In _xGa _(1-x)N/GaN heterostructures grown with the metal-organic chemical vapor deposition (MOCVD) technique with different In _xGa _(1-x)N 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 In _xGa _(1-x)N back-barrier and the surrounding layers.