High Density Exciton Luminescence Mechanism Based On The Measuring Of PL Spectrums Of Gan Materials

The commercialization of GaN based on semiconductor devices gives a boost to the rapid development in III-Nitrides researching fields. Since the band gap can be consistently tuned from0.7eV to6.2eV and covers the extensive spectrum range between near-infrared to ultraviolet, GaN based semiconductors are the most favorite materials for optoelectronic device applications, which naturally makes the studies of their optical and electrical properties the kernel issues in the research field. Nowadays, with the theory and technology development, these researches and applications are much more diverse and intensive. Recently, the characteristics of the ternary alloy of III-Nitrides and its photoelectron devices are becoming most prosperous topics in III-Nitrides research.Based on the optical characteristics of the III-Nitrides, this thesis is composed experiments of the low temperature variable power PL spectrums of both GaN films and InGaN/GaN Nanorods quantum well. These experiments focus on excitons binding regulation and high-density exciton luminescence mechanism.Based on the measuring of the PL spectrums of GaN membrane samples, conclusions are listed as follows, which involve the research of distribution and degradation of excitons under the condition of high-density injection.1. Under high-intensity excitation, the formation of free excitons is suppressed while bound excitons can still form, and become the main channel of compounding.2. In high quality GaN materials, bound excitons exciton are more effective than free exciton s in forming compound channels. The donor bound excitons emit super-fluorescent under high intensity excitation.3. The phenomenon of blue shift under the conditions of one-level LO energy difference and high intensity excitation shows that non-equilibrium current carriers are proved to be in high energy-state distribution.4. Active current carriers in radiation compound varies with the excitation intensity, under the condition of more than15kw/cm2excitation, there exist factors inhibiting the light-emitting.But super fluorescence can cross the limits.5. Quality of materials gives practical influence to excitonic luminescence. Of the three GaN samples, the luminescence of GaN in sapphire proves the weakest.On the other hand, experiments on the PL spectrums of InGaN/GaN Nanopillars quantum well lead us to believe:1. Regardless the In composition content, with Ni samples on the top of the nanopillars and under the same conditions, the luminescence intensity are increased by3to5times, so we can conclude that Ni gives inducement to compound luminescence.2. Under high-intensity excitation, in the case of the single compound level, such as high In content samples, with increasing excitation intensity, there is always inflection points in luminescence growth, and the time is almost at the same point, which proves that the compounding of free excitons is suppressed.3. Under high-intensity excitation, in the case of the single compound level, such as high In content samples, as excitation intensity increases, the peak value exceeds power8, and the suppression of the free exciton compounding is broken through., which leads to super fluorescence.4. Under high-intensity excitation, in the case of the single compound level, such as low In content samples, as excitation intensity increases, no inflection points in luminescence growth is found, which shows that free exciton compounding has not been suppressed. But the peak energy value is only power7and super fluorescence is not found.