Widegap Semiconductor III-Nitride Research

Abstract : By the onset of the project many aspects of optical properties of InGaN semiconductors were unknown. From the literature publications, it was known that they strongly depend on the micro-and nanostructure of the semiconductor. S This need of further investigation was spurred by the across-the-board advances in the preparation of the high-brightness light-emitting devices in the blue region of the spectrum, which was difficult to obtain by other means. Over 3 years of the project we made new advances in the investigation of the mechanism of the light emission in InGaN. As expected, it was identified that the emission mechanism in InGaN is the recombination of electrons and holes. InGaN was made by two methods: molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD). Substantial problem was found in the correlation of the emission parameters of InGaN and method of their preparation, however eventually it was largely sorted out with the help of atomic force microscopy. It was firmly established that the traps on inhomogeneities act as centers for light emission and the LED activity should be attributed to this feature of the semiconductor. Strong evidence of the participation of nanoscale In quantum dots in the light-emitting process was the major objective of this 3-year project.