Structural and electrical characteristics of GaN, n-GaN and A1xGa1−xN

GaN, n-GaN (n∼̴ 1 × 1018/cm3) and AlxGa1−xN (x = 0. 14, 0.26, 0.45) were epitaxially grown by metal organic chemical vapor deposition (MOCVD) on c-plane sapphire substrate. The composition and thickness of AlxGa1-xN layers were found by employing ω-2θ scan with simulation fit. The dislocation densities of epilayers were determined from symmetric and asymmetric planes of ω-scan rocking curve. The (105) plane reciprocal space mapping was employed to measure the in-plane strain (εxx) of the AlxGa1−xN layers grown on GaN. The in-plane strain of GaN and n-GaN were calculated from 2θ scan. The second derivative of the capacitance of the AFM tip-sample system was determined using electrostatic force microscopy (EFM). Photon decay time was measured using time resolved photoluminescence and the results correlated with structural property of the epilayers. The Schottky behavior of Ni/Au contacts on grown layers were studied using current-voltage (I-V) measurements. The Schottky barrier height of each device was compared with the edge dislocation density of the layers.