Reduction of threading dislocations in GaN on in-situ meltback-etched Si substrates

InGaN/GaN Blue Light Emitting Diodes Using Freestanding GaN Extracted from a Si Substrate

“…Meanwhile, it has been impossible to obtain freestanding GaN wafers grown on a Si substrate because of the large lattice mismatch (16.9%) and the difference between the thermal expansion coefficients of GaN (αa = 5.59 × 10 –6 /K) and Si (αa = 3.77 × 10 –6 /K). These factors impede the growth of freestanding GaN on Si substrates because they lead to formation of cracks and large bowing, owing to a high tensile stress on thick GaN layers grown when the reactor cools from the growth temperature to room temperature after the growth. − Moreover, the reaction between Ga and Si due to the out-diffusion of Si atoms into the GaN layers, namely, the meltback effect, renders it even more difficult to obtain freestanding GaN wafers using Si substrates. , Recently, we fabricated and characterized a 2 in. freestanding GaN crystal, 400 μm in thickness and 5 μm in wafer bowing, grown using Si substrates by HVPE, which was achieved by in situ removal of the Si substrate .…”

“…16−18 Moreover, the reaction between Ga and Si due to the out-diffusion of Si atoms into the GaN layers, namely, the meltback effect, renders it even more difficult to obtain freestanding GaN wafers using Si substrates. 19,20 Recently, we fabricated and characterized a 2 in. freestanding GaN crystal, 400 μm in thickness and 5 μm in wafer bowing, grown using Si substrates by HVPE, which was achieved by in situ removal of the Si substrate.…”

Microstructure of PAMBE-grown InN layers on Si(111)

“…Ishikawa et al [32] reported a meltback reaction for GaN grown on Si(111). Recently, Ishikawa and Shimanaka [33] studied meltback reactions of Ga, Al and In with Si by depositing these metals on Si-substrates. Atomic force microscopy revealed the depth of the meltback regions, which corresponds well to the depth of the trapezoidal structures in our specimens and the samples analyzed by Kaiser et al [31].…”

Surface Modification on Wet-Etched Patterned Sapphire Substrates Using Plasma Treatments for Improved GaN Crystal Quality and LED Performance

“…The residual Ga droplets act as nucleation seeds to grow high quality GaN films. 18,19 Since the GaN decomposition rate was higher than the Ga desorption rate, many Ga droplets were left on the sapphire, with roughness of several tens of nanometers; another GaN layer was grown on these droplets, leading to improved GaN crystal quality. A similar growth mode occurred in our case; the new GaN nucleation layer formed by Ga droplets promoted vertical GaN growth on the slightly roughened PSSs and resulted in a low dislocation density GaN film (Figs.…”