High-quality GaN epitaxial layer grown by metalorganic vapor phase epitaxy on (111) MgAl2O4 substrate

Abstract

We grew GaN crystals by metalorganic vapor phase epitaxy on (111) and (100) MgAl2O4 substrates. We obtained a single-crystal GaN layer with a specular surface on the (111) substrate. The full width of half-maximum of the x-ray rocking curve for a 3.6 μm thick GaN layer was 310 s, comparable to the reported values for GaN on Al2O3 substrates. In the room-temperature photoluminescence, a band-edge emission at around 360 nm was dominant. A smooth cleaved (11̄00) facet of the GaN epitaxial layer was obtained, assisted by the inclined (100) cleavage of the (111) MgAl2O4 substrate. We intend this cleaved facet, which is normal to the surface, to be used as a cavity mirror in a laser diode.

Alumina-rich spinel: A new substrate for the growth of high quality GaN-based light-emitting diodes

“…1. Finally, contrary to c-plane sapphire, (1 1 1)-oriented spinel exhibits oblique (0 0 1)-cleavage planes propagating perpendicularly to the surface in the above-laying GaN, thus facilitating the formation of parallel facets for the realization of horizontal-cavity GaN-based laser diodes (LDs) [5,8].…”

“…3 The thermal mismatch is respon- ). Stoichiometric spinel (MgAl 2 O 4 , n ¼ 1), which has been studied extensively for GaN heteroepitaxy since 1995 [5][6][7][8][9][10], has given very promising results. Unfortunately, the brittleness of this material makes it very difficult to grow and process as wafers, so that the manufacture of large diameter wafers at a reasonable cost is most unlikely.…”

Structure, thermal expansion and optical property of alumina-rich spinel substrate

“…However, large mismatches in lattice constant (16%) and thermal expansion coefficient (34%) between GaN and Al 2 O 3 cause the stress problems [5,6], such as cracking, wafer bowing and high density of crystalline defects. Furthermore, Al 2 O 3 has little tendency toward cleavage, and the (11 0 0) cleavage plane of GaN is rotated 30 • from the (11 0 0) cleavage plane of Al 2 O 3 [7]. It is almost impossible to realize cavity mirrors of laser diodes by the cleavage.…”

Selective excitation of the yellow and blue luminescence in n- and p-doped Gallium Nitride

“…GaN growth in both of those cases was obtained through metalorganic chemical vapor deposition (MOCVD). Some more recent efforts to reduce the amount of defects in GaN even further include (a) using substrates made from SiC [14], spinel (MgAl 2 O 4 ) [15], or other materials (which may have a more closely matched lattice constant), (b) using the technique of lateral epitaxial overgrowth [16], and (c) growing bulk (non-epitaxial) samples under high pressure [17].…”