Alternately double‐sided growth of low‐curvature GaN templates on sapphire substrates using hydride vapor phase epitaxy

Abstract

GaN layers have been grown on double‐side‐polished sapphire substrates using hydride vapor phase epitaxy. The GaN layers on each side of the substrate were alternately grown using a new susceptor with a rotating mechanism. Although a conventional GaN layer grown on one side of a sapphire substrate exhibits a small radius of curvature, the alternately double‐sided‐grown GaN template exhibits a large radius of curvature. The radius of curvature of the alternately double‐sided‐grown GaN template with a thickness of 180 μm was found to be approximately 16.4 m, and was larger than the 0.5 m radius of curvature of the conventional GaN template.

A bow-free freestanding GaN wafer

“…The bow can cause GaN wafer cracking and peeling-off during the GaN lm growth through MOCVD and a misalignment of the LED patterns through lithography. 20 Thus, many studies on suppressing the bow in the growth process of an epitaxial GaN layer have been conducted using various technologies, such as the change in the III-V gas ratio for a stress-relaxed GaN layer, 21 self-separating GaN from the substrate, 22 simultaneous double-side growth of a GaN layer on a sapphire substrate, 23 and hydrogen-ion implantation for stress relaxation. 24 Even though the GaN wafer bow can be suppressed by the growth techniques, it uctuates during the wafering process, which makes a prediction of a nal GaN wafer bow very difficult.…”