Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 50: Poster II

HL 50.25: Poster

Donnerstag, 30. März 2006, 16:30–19:00, P3

AlGaN templates on sapphire — •Kai Otte, Tomohiro Yamaguchi, Stephan Figge, and Detlef Hommel — Universität Bremen, Otto-Hahn Allee 1, 28359 Bremen

To grow unstrained AlInN/GaN vertical cavity surface emitting laser (VCSEL) structures with high aluminium content one needs templates with a higher lattice constant than GaN. This can be reached by adding aluminium to the GaN template layer.
We report on the growth of AlGaN templates by metal organic vapor phase epitaxy on sapphire. The 2 µm thick AlGaN layers with an aluminium mole fraction of 0.25 were grown on low temperature AlGaN nucleation layers.
High resolution x-ray diffraction and scanning electron microscopy data showing crack-free and compressively strained (є_xx,yy=0.3 at room temperature) templates will be presented. The templates show no compositional fluctuation in growth direction.
Reflectometry measurements during growth show no three dimensional island growth but two dimensional growth. This points to a high defect density. To reduce this effect different nucleation layers were grown.
These templates are promising for the growth of VCSEL structures. A comparison of distributed Bragg reflectors grown on AlGaN and GaN templates will be shown.