We have investigated the crystalline morphology such as lattice plane curvature and lattice plane tilting in (20-21) GaN films on (22-43) patterned sapphire substrates (PSS) by using X-ray rocking curve (XRC) measurements. The results of the symmetric XRC for the GaN (20-21) plane showed anisotropic lattice plane curvature between the [À1014] and [À12-10] directions. This is due to the large difference of the thermal expansion coefficient in the [0001] direction between GaN and sapphire. From the results of asymmetric XRC for the and (12-31) diffractions, it is found that lattice plane tilting is highly dependent on the film thickness and the growth condition. The Àc-plane-suppressed growth process with tuning the V/III ratio for the (20-21) GaN films on the (22-43) PSS is very effective to suppress the generation of basal plane stacking faults as confirmed by TEM analysis.

Defect reduction methods for III-nitride heteroepitaxial films grown along nonpolar and semipolar orientations P Vennéguès Defects in semipolar (11bar2bar2) ZnO grown on (112) LaAlO3/(La, Sr)(Al, Ta)O3 substrate by pulsed laser depositionWe have investigated the position dependence of crystalline quality and defect distribution in a semipolar ð2021Þ hydride vapor phase epitaxy (HVPE)-GaN film grown on a ð2243Þ patterned sapphire substrate (PSS). Position-dependent X-ray microdiffraction (XRMD) measurement clearly revealed the periodic fluctuation of the 20 21 lattice plane tilting in HVPE-GaN films. This correlated with the periodic distribution of (a + c)-type dislocations owing to the patterning pitch of the PSS as confirmed by transmission electron microscopy (TEM). In the three-dimensional reciprocal lattice space map, the diffuse streak exactly along the c-axis can be clearly detected, indicating the presence of basal plane stacking faults in HVPE-GaN films. Furthermore, we have quantitatively estimated the defect densities from the results of XRMD and TEM measurements. From the obtained results of XRMD and TEM measurements, the fluctuation of the lattice plane tilting and the defect distribution in ð2021Þ HVPE-GaN films grown on two types of metalorganic vapor phase epitaxy-GaN templates will be discussed in detail.

No abstract