Thickness and growth condition dependence of crystallinity in semipolar (20–21) GaN films grown on (22–43) patterned sapphire substrates

Abstract

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.

Polychromatic emission from polar-plane-free faceted InGaN quantum wells with high radiative recombination probabilities

“…The ð000 1Þ planes have also been observed in selective area MOVPE of GaN on the nonpolar and semipolar planes. [16][17][18][19][20] It has been pointed out that the −c growth promotes the inclusion of stacking faults. 20) To confirm whether this also occurs in our samples, CL mapping was performed for a sample with FF = 0.25, which has a structure similar to sample E, but the inverted trapezoids do not coalesce.…”

“…[16][17][18][19][20] It has been pointed out that the −c growth promotes the inclusion of stacking faults. 20) To confirm whether this also occurs in our samples, CL mapping was performed for a sample with FF = 0.25, which has a structure similar to sample E, but the inverted trapezoids do not coalesce. It was found that there were no dark lines in the areas corresponding to the −c growth front, which suggested the absence of stacking faults.…”

Positional dependence of defect distribution in semipolar hydride vapor phase epitaxy-GaN films grown on patterned sapphire substrates

“…By comparing samples A and B, since the HVPE-GaN growth conditions were the same for both samples, the reduction in BSF width was considered to be due to the use of the MOVPE-GaN template with the −c-plane-suppressed growth. 17) Many threading dislocations were also observed in both samples. From the results of g · b (b: Burgers vector) analysis, the Burgers vectors of these dislocations can be identified to be of the (a + c)-type.…”

“…In this study, two types of MOVPE-GaN templates were prepared; either normal growth or −c-direction-suppressed growth was selected by tuning the V=III ratio and growth temperature appropriately. 17) After fabricating MOVPE-GaN templates, a 40-µm-thick HVPE-GaN film was grown on each MOVPE-GaN template. The HVPE-GaN film was grown at a V=III ratio of 10 at 1040 °C.…”