Solid State Physics Seminar

Despite of the big progress obtained with group-III nitrides (AlGaInN) in last 3 decades (blue LED’s and LD’s,,solid state lighting and electronic devices) further applications are still hampered by internal material limitations like insufficient p-dopability of high-Al containing compounds needed for deep-UV emitters. In this respect many efforts are made to extend the functionalities of the nitrides by alloying them with other elements like B, P, Sb, Mn or As. This seminar will give an overview on our efforts to introduce arsenic into Ga(Al)N as well by MBE and MOVPE as growth methods. Using MOVPE homogeneous As concentrations up to 7.6% could be obtained whereas the As incorporation in MBE growth was limited to 1%. The influence of the As-content the Ga(Al)N matrix on the band structure will be discussed as well as potential applications for electronic and light emitting devices. On the other hand when changing the MBE growth conditions from nitrogen-rich to gallium-rich a self-initiated VLS-growth (vapor-liquid-solid) of regular GaN-columns with dodecagonal walls is observed. Usually all nitride-based columns are hexagonal in their shape. This is the first finding of such dodecagonal rods with stable a- and m-plane walls. The underlying physical mechanisms and the stability of the a- and m-planes will be explained in detail. Applications of such microcolumns for water splitting and UV-emitters will be presented. Research Group Lider EpiMat (Advanced Epitaxial Materials)Director of the Material Science and Engineering Center at PORT