Comparative study of AlGaN/GaN heterostructures grown on different sapphire substrates

Application of patterned sapphire substrate for III-nitride light-emitting diodes

“…134 It indicates that the crystalline quality does not show an absolute dependence on the pattern size, and epilayers grown on MPSS show better crystal quality than NPSS in some cases. 135 As the parameters of patterns for sapphire substrate will remarkably influence LEE, the LEE of LEDs on PSS is expected to be further improved when the pattern size varies from the micrometre to nanometre. However, it is noted that the strong diffraction induced by near-wavelength-scale patterns will not enhance the LEE of LEDs effectively.…”

“…134 It indicates that the crystalline quality does not show an absolute dependence on the pattern size, and epilayers grown on MPSS show better crystal quality than NPSS in some cases. 135…”

Effect of grain coalescence on dislocation and stress in GaN films grown on nanoscale patterned sapphire substrates

“…24,25 Notably, the density of GaN grain coalescence at the top of the cone-shaped pattern of the NPSS increases by one to two orders of magnitude compared to that of the MPSS, which poses challenges in controlling dislocations at the coalescence boundaries. 29,30 Nonetheless, recent research has revealed that precisely controlling grain orientation by nanopatterned substrates can almost eliminate dislocations in AlN films at the coalescence boundaries. 31 Accordingly, further investigations focusing on the coalescence of GaN grains on NPSSs are required to realize high-quality GaN films.…”

Crystal Structure and Surface Morphology of GaN Thin Films Grown on Different Patterned AlN Substrate Surfaces

“…Interest in atomic layer deposition (ALD) technology is increasing due to the focus on microelectronics and deep submicron chip technology, which demand smaller device and material sizes. , The majority of GaN thin films deposited on sapphire or GaN substrates. − Nevertheless, the lattice mismatch exists between sapphire substrate and GaN. − To address this issue, aluminum nitride (AlN) has been widely used as a buffer layer to enhance the crystalline quality of GaN thin films. , Additionally, AlN films fabricated via the plasma-enhanced atom layer deposition (PEALD) process were utilized by Zhang et al as a passivation layer on the AlGaN/GaN surface . Therefore, it is crucial to investigate how different AlN buffer layer characteristics affect the formation of GaN thin films to improve the quality of the GaN thin films and increase the efficiency of LEDs made with GaN.…”