The PIs propose to study the light emission processes and develop novel light emitting devices based on the ZnO/GaN system. Our preliminary studies indicate that ZnO films grown epitaxially on GaN on Sapphire by pulsed laser deposition (PLD), are of high crystalline and optical quality. The quality of the films is such that the excitonic luminescence intensity produced is four to five times higher than that seen in the best quality GaN layers [1]. Furthermore, reports indicate [2] that ZnO has higher optical gain (300 cm-') than GaN (100 cm-') at room temperature (RT), and higher exciton binding energy (60 meV versus 28 meV for GaN)[3], thus suggesting a strong potential for ZnO to become a more efficient room temperature UV-blue light emitter than GaN. Our proposal seeks to understand and improve the optical capabilities of this material system, and develop prototype light emitting devices. Our work will include: (a) the PLD growth of multilayered structures, the study, modeling, and simulation of the growth processes for improved film and interface quality, (b) the investigation of the light emission processes (radiative/non-radiative recombination, spontaneous/stimulated emission) with respect to the structural (defects/strain), electronic (impurity incorporation/field effects), and optical properties of the grown films, and (c) the design and fabrication of prototype UV-blue light emitting devices and test structures, ranging in sizes from microns down to nanoscale dimensions using both photolithographic techniques and focused ion beam (FIB) technology. ***
