Abstract
Functional non-oxide ceramic materials have gained a great interest for potential applications in opto-electronic device industries. In particular, the wide band-gap semiconductor GaN and new superconducting MgB2 ceramics have been intensively studied in micro/nanometer scaled electronics. However, their thermodynamic nature of low-temperature decomposition makes it difficult to densify highly using a conventional sintering technique, which limits the application of these materials to various deposition processes which need the highly-densified bulk target. We have succeeded in densifying GaN and MgB2 up to 98% RD without any additive using a pulsed electric current-activated sintering technique and investigated the microstructural features of the sintered bodies using a variety of microscopic tools including SEM and TEM. In addition, amorphous GaN nanoparticles/film and superconducting MgB2 thin film have been successfully prepared using a pulsed-laser ablation of these sintered pellets, resulting in the quantum confinement effect in the small sized GaN (~5nm), blue luminescence (~2.8eV) from amorphous GaN film and high Tc MgB2 thin film comparable to that of MgB2 bulk. These results suggest that our approach be greatly effective for micro/nano scaled fabrication of these materials, leading to the high efficiency of the electronic device process.
