Growth of semipolar {20–21} GaN and {20–2–1} GaN for GaN substrate

Abstract

In this article, we present a semipolar {20–21} GaN layer and {20–2–1} GaN layer for large GaN substrates. The {20–21} GaN layer was fabricated on {22–43} patterned sapphire substrates (PSSs) by metal‐organic vapor‐phase epitaxy (MOVPE) and hydride vapor‐phase epitaxy (HVPE). We found that the surface roughening and crack generation during the HVPE growth were suppressed by the formation of SiO2‐striped masks parallel to the c‐axis on the MOVPE‐grown {20–21} GaN template. Furthermore, we demonstrated millimeter‐thick crystal growth on a {20–21} GaN layer and a {20–2–1} GaN layer on a GaN substrate using HVPE. The dark‐spot density in the {20–2–1} GaN layer was approximately 9.6 × 106 cm−2 for 960 min growth. The dark‐spot density in the {20–2–1} GaN layer decreased more rapidly than that in the {20–21} GaN layer as growth thickness increased.

Structural study of GaN grown on nonpolar bulk GaN substrates with trench patterns

“…Recently, the method of preparing high-quality freestanding GaN substrates has become well established. 4,5) Nevertheless, the present LEDs or LDs grown on the (0001) plane suffer from the quantumconfined Stark effect (QCSE) because of the large polarization-related internal electric field in the active layer of LEDs or LDs. 6) This effect causes band bending in the active layer and the spatial separation of electrons and holes in the quantum wells (QWs) and lowers the radiative recombination efficiency.…”

High-quality, 2-inch-diameter m-plane GaN substrates grown by hydride vapor phase epitaxy on acidic ammonothermal seeds

“…Different strategies have been reported to reduce the density of these defects; for example, non-or semipolar GaN layers were grown by sidewall epitaxial lateral overgrowth (SELO) on nonpolar GaN templates, 15,17) 4H-SiC, 18) and patterned sapphire substrates. [19][20][21][22] However, the templates and substrates obtained using the SELO method have periodic areas of high defect density due to coalescence and c-plane growth.…”