Cathodoluminescence and field emission from GaN/MgAl₂O₄grown by metalorganic chemical vapor deposition: substrate-orientation dependence

Abstract

GaN films with single-crystalline and polycrystalline structures were deposited by metalorganic chemical vapor deposition (MOCVD) on ( 111) and (100) MgAl 2 O 4 substrates modified by chemical etching and thermal passivation. The oriented GaN films on the as-processed (111) MgAl 2 O 4 substrate revealed broad visible emission band bands at 3.2 eV and a sharp luminescence peak centered at 1.8 eV in room temperature cathodoluminescence measurements, which can be attributed to the recombination of donor-acceptor pairs and GaN-related emission, respectively. Field emission (FE) measurements demonstrated that the oriented nanostructured 150 nm-thick GaN film on the as-processed (111) MgAl 2 O 4 substrate has an ultralow turn-on-field of 4.29 V mm À1 at 10 nA cm À2 and a stable emission of 0.028 mA cm À2 with 5% current density fluctuation for 22 h without any degradation. Compared to GaN films on as-processed (100) MgAl 2 O 4 substrate, the mechanism for the improved performance in optical and FE properties of the GaN film on as-processed (111) MgAl 2 O 4 substrate has been investigated in detail.

Epitaxial growth of group III-nitride films by pulsed laser deposition and their use in the development of LED devices

“…17, has a small lattice mismatch with group III-nitride films, as listed in Table 1, and is therefore a suitable substrate for epitaxial growth of group III-nitrides [83][84][85]. However, the MgAl 2 O 4 substrate has high partial Mg pressure [83,84].…”

Current-Fluctuation Mechanism of Field Emitters Using Metallic Single-Walled Carbon Nanotubes with High Crystallinity

“…A CL device that uses a field emitter as a cathode electrode radiates rays that considerably fluctuate or flicker. The fluctuation or flicker from a CL device mainly has low frequencies of under 200 Hz [5][6][7][8][9][10]. On the basis of the above problems, a cathode structure that can reduce the fluctuation of emission has been studied [9,10].…”