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GaN-based micro light emitting diodes (micro-LEDs) on silicon (Si) substrates with 40 μm in diameter are developed utilizing standard photolithography and inductively coupled plasma etching techniques. From current-voltage curves, the relatively low turn-on voltage of 2.8 V and low reverse leakage current in the order of 10 −8 A/cm 2 indicate good electrical characteristics. As the injection current increases, the electroluminescence emission wavelength hardly shifts at around 433 nm, and the relative external quantum efficiency slightly decays, because the impact of quantum-confined Stark effect is not serious in violet-blue micro-LEDs. Since GaN-LEDs are cost effective on large-area Si and suitable for substrate transfer or vertical device structures, the fabricated micro-LEDs on Si should have promising applications in the fields of high-resolution display and optical communication.

Microstructures of GaN buffer layers grown on Si (111) substrates using rapid thermal process low-pressure metalorganic chemical vapor deposition are investigated by an atomic force microscope (AFM) and a high-resolution transmission electron microscope (HRTEM). AFM images show that the islands appear in the GaN buffer layer after annealing at high temperature. Cross-sectional HRTEM micrographs of the buffer region of these samples indicate that there are bunched steps on the surface of the Si substrate and a lot of domains in GaN misorienting each other with small angles. The boundaries of those domains locate near the bunched steps, and the regions of the film on a terrace between steps have the same crystal orientation. An amorphous-like layer, about 3 nm thick, can also be observed between the GaN buffer layer and the Si substrate.

GaN/Pb(Zr0.53Ti0.47)O3 structures have been fabricated by light radiation heating low-pressure metal-organic chemical deposition and pulsed laser deposition. These structures show leakage current lower than 10-11 A at applied voltage of 5 V. X-ray diffraction shows that ferroelectric Pb(Zr0.53Ti0.47)O3 films directly on GaN are well crystallized with perovskite structure. Because of the high thermal stability and relatively smaller mismatch between GaN and ferroelectrics in comparison with that of Si/ferroelectric structures, GaN looks like more promising as semiconductor active layer for metal-ferroelectric-semiconductor field effect transistors.