Effects of growth rate of a GaN buffer layer on the properties of GaN on a sapphire substrate

Abstract

We studied the effects of the growth rate of a GaN buffer layer grown on a GaN epilayer. It was found that this growth rate plays a key role in improving the quality of the GaN film on a sapphire substrate and an optimum growth rate exists that yields the best crystal quality. A GaN film grown on a buffer layer with the optimum growth rate of 18.3 nm/min has an electron Hall mobility of 539 cm2/V s and a dislocation density of approximately 2×108 cm−2. These improvements of GaN film qualities are illustrated by the promotion of the lateral growth mode.

Formation of vertically aligned ZnO nanorods on ZnO templates with the preferred orientation through thermal evaporation

“…The rapid growth rate of the initial seed crystals causes the threedimensional (3D) island-shaped growth and the randomness of the (0 0 1) plane showing no preferred orientation. For the growth of the heterostructures with a large lattice mismatch (example: GaN or ZnO on sapphire or Si), the structural properties of the initial layers such as buffer layers, significantly affect those of the whole film [15,16]. Similarly, the reason being considered for the random inclination of the ZnO nanorod's [0 0 1] ZnO on a [1 1 1] Si substrate is that the seed crystals had no preferred orientation in the initial stage, or that the (0 0 1) planes were random, which can be confirmed by the DP from the ZnO near the ZnO seed crystal/Si substrate interface, showing the same direction as that shown by the (0 0 2) diffraction spots of the ZnO seed crystal and nanorod, as shown in the insets of Fig.…”

Understanding GaN nucleation layer evolution on sapphire

“…Changes in the NL growth parameters such as thickness [8,[12][13][14][15], growth T [16][17][18], growth rate [19][20][21], annealing schedule from low to high T [13,[22][23][24], and extent to which the sapphire surface is exposed to NH 3 prior to NL growth [15,17,25] have all been shown to influence the NL growth and subsequent quality of the high-T GaN layers.…”

Efficiency Improvement of Blue LEDs Using a GaN Burried Air Void Photonic Crystal With High Air Filling Fraction

“…It can be seen that the PSS LED with BAVPC (righthand side of x-axis) exhibits the lowest FWHM of (002) and (102) diffraction peaks as compared to the C-PSS LED (lefthand side of x-axis) and FSS LED with BAVPC (centre of x-axis). The FWHM of (102) diffraction peak is related to the densities of TDs and edge dislocations [31], [32]. In addition, the FWHM of the (002) diffraction peak depends on screw and mixed-type dislocations.…”