Growth of Freestanding Gallium Nitride (GaN) Through Polyporous Interlayer Formed Directly During Successive Hydride Vapor Phase Epitaxy (HVPE) Process

Abstract

The progress of nitride technology is widely limited and hindered by the lack of high-quality gallium nitride (GaN) wafers. Therefore, a large number of GaN epitaxial devices are grown on heterogeneous substrates. Although various additional treatments of substrate have been used to promote crystal quality, there is still plenty of room for its improvement, in terms of direct and continuous growth based on the hydride vapor phase epitaxy (HVPE) technique. Here, we report a three-step process that can be used to enhance the quality of GaN crystal by tuning V/III rate during successive HVPE process. In the growth, a metal-organic chemical vapor deposition (MOCVD) grown GaN on sapphire (MOCVD-GaN/Al2O3) was employed as substrate, and a high-quality GaN polyporous interlayer, with successful acquisition, without any additional substrate treatment, caused the growth stress to decrease to 0.06 GPa. Meanwhile the quality of GaN improved, and the freestanding GaN was directly obtained during the growth process.

Surface ligand removal in atomic layer deposition of GaN using triethylgallium

“…It can be noted that the B-pulse does not seem to affect the crystallinity of the films. For the ABC-type approach presented in this manuscript, the film density was found to be 5.4 g/cm 3 (no B-pulse), 5.0 g/cm 3 (Ar-plasma as B-pulse), 4.9 g/cm 3 (H 2 -gas as B-pulse), and 5.6 g/cm 3 (H 2 -plasma as B-pulse) which should be compared to 6.15 g/cm 3 for bulk GaN. Thus, the B-pulse has a slight effect on the film density.…”

“…GaN thin films are typically deposited by chemical vapor deposition (CVD) at 800-1000°C using trimethylgallium, Ga(CH 3 ) 3 (TMG), and ammonia, NH 3 , as precursors. 3 The high deposition temperatures and poor conformity of the established CVD processes for GaN are problematic for any device structure not compatible with high temperatures or that require uniform film thickness over topographically complex geometries. The deposition method of choice for such structures is atomic layer deposition (ALD).…”

Surface Ligand Removal in Atomic Layer Deposition of GaN Using Triethylgallium

“…It can be noted that the B-pulse does not seem to affect the crystallinity of the films. For the ABC-type approach presented in this manuscript, the film density was found to be 5.4 g/cm 3 (no B-pulse), 5.0 g/cm 3 (Ar-plasma as B-pulse), 4.9 g/cm 3 (H2-gas as B-pulse), and 5.6 g/cm 3 (H2-plasma as B-pulse) which should be compared to 6.15 g/cm 3 for bulk GaN. Thus, the B-pulse has a slight effect the film density.…”

“…GaN thin films are typically deposited by chemical vapor deposition (CVD) at 800-1000 °C using trimethylgallium, Ga(CH3)3 (TMG), and ammonia, NH3, as precursors. 3 The high deposition temperatures and poor conformity of the established CVD processes for GaN are problematic for any device structure not compatible with high temperatures or that require uniform film thickness over topographically complex geometries. The deposition method of choice for such structures is atomic layer deposition (ALD).…”

Advancements in energy efficientGaNpower devices and power modules for electric vehicle applications: a review

“…Furthermore, the hydrogenated vapor phase epitaxial growth (HVPE) method is widely used for the mass fabrication of the GaN crystals. 5 This method features in high material purity along with a growth rate of 100 μm/h. However, the crystals still face the problem of using foreign substrates as seeds.…”