Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 2: GaN: devices

HL 2.6: Talk

Monday, March 23, 2009, 11:45–12:00, BEY 118

Barrier alloy composition and polarization control in nitride light emitters — •Christoph Hums, Aniko Gadanecz, Armin Dadgar, Jürgen Bläsing, Alexander Franke, Thomas Hempel, Jürgen Christen, and Alois krost — Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg

Although InGaN based light emitting diodes (LEDs) have been commercialized for general lighting applications and displays, they suffer from reduction in efficiency and a pronounced luminescence blue shift at high injection current levels. This behavior can be attributed to the strong polarization fields in c-direction of the active region and the associated quantum confined stark effect (QSCE). To reach higher external quantum efficiencies (EQE) the reduction of the polarization fields is inevitable. Most attempts in reducing the internal fields target on switching the direction of the quantum wells (QWs) from c-plane in a direction with reduced fields (e.g. a-plane). A new approach is polarization control by new barrier- and QW-materials as the ternary AlInN and the quaternary AlInGaN. We will present calculations of the internal polarization fields in the proposed structures, which allow an estimate of the needed alloy compositions. Then the growth of AlInN with high indium content will be discussed. The limits of indium incorporation, the critical layer thickness on GaN and its impact on the novel structures will be displayed.