Sandwich method to grow high quality AlN by MOCVD

Abstract

We report pulsed atomic layer epitaxy growth of a very high crystalline quality, thick (~2 µm) and crack-free AlN material on c-plane sapphire substrates via a sandwich method using metal organic chemical vapor deposition. This sandwich method involves the introduction of a relatively low temperature (1050 °C) 1500 nm thick AlN layer between two 250 nm thick AlN layers which are grown at higher temperature (1170 °C). The surface morphology and crystalline quality remarkably improve using this sandwich method. A 2 µm thick AlN layer was realized with 33 arcsec and 136 arcsec full width at half maximum values for symmetric and asymmetric reflections of ω-scan, respectively, and it has an atomic force microscopy root-mean-square surface roughness of ~0.71 nm for a 5 × 5 µm2 surface area.

Growth Temperature Dependency of High Al Content AlGaN Epilayers on AlN/Al2O3 Templates

“…A~20 nm thick low temperature AlN nucleation layer then 300 nm thick high temperature PALE (pulsed atomic layer epitaxy) AlN were grown on sapphire substrate. Growth details of this AlN/sapphire template were explained in detail in previous studies [8,14]. Three (A, B and C) different AlGaN epilayers were grown on optimized AlN/sapphire template at 1020, 1180 and 1220 C, respectively.…”

Effect of V–III Ratio‐Based Growth Mode on the Surface Morphology, Strain Relaxation, and Dislocation Density of AlN Films Grown by Metal‐Organic Chemical Vapor Deposition

“…substrates, [28][29][30] and manipulating the growth mode via temperature or V-III ratio. [31][32][33][34] Imura et al have reported the varying V-III ratio multilayer transition growth method to improve AlN crystalline quality, which gradually changed from high ammonia (NH 3 ) flow rate at buffer layer to low flow rate at top layer. [31] They have confirmed that regulating the V-III ratio could promote the dislocation annihilation.…”

The Effect of Si (111) Substrate Surface Cleaning on Growth Rate and Crystal Quality of MOVPE Grown AlN

“…Therefore, AlN-based devices are generally grown on silicon and sapphire substrates. The heteroepitaxial growth of the high crystal quality AlN epitaxial layer on different substrates is one of the most important problems in the literature [15]. AlN layer can be grown more difficult for reasons such as growth at higher temperatures (~ 1200 °C) compared to GaN [16], the high parasitic reaction between TMAl (Al(CH3)3) and NH3 [17], and the low surface mobility of the Al atom [18].…”