Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 80: GaN: Preparation and Characterization V (mainly Cathodoluminescence)
HL 80.6: Talk
Thursday, March 29, 2012, 12:30–12:45, ER 270
Electro- and cathodoluminescence microscopy of an InGaN/GaN LED structure based on semipolar {10-11} faceted GaN pyramids — •Martin Thunert1,3, Sebastian Metzner1, Thomas Hempel1, Frank Bertram1, Jürgen Christen1, Clemens Wächter2, Michael Jetter2, and Peter Michler2 — 1Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — 2Universität Stuttgart, Institut Für Halbleiteroptik und Funktionelle Grenzflächen, Germany — 3Universität Leipzig, Institut für Experimentelle Physik II, Linnéstraße 5, 04103 Leipzig
The luminescence distribution of an InGaN/GaN LED structure grown by selective MOVPE is analyzed by spatially and spectrally resolved electroluminescence (EL) and cathodoluminescence (CL) microscopy at room temperature. Self organized grown hexagonal GaN pyramids have been selectively overgrown by an InGaN/GaN MQW and subsequently metal contacts complete the LED structure. By CL measurements a homogeneous InGaN luminescence distribution over the semipolar side facets as well as a red shifted emission on the top and the corner of the pyramid was observed due to higher indium incorporation. In contrast, EL investigations of the identical pyramid show a continuous shift of the InGaN emission caused by inhomogeneous lateral current distribution. With increasing injection current the spatially averaged EL peak of the investigated pyramid reveals a very strong blueshift of 290 meV and a high increase in intensity indicating screening of the QCSE and filling of potential fluctuations or local inhomogeneities due to the formation of new current paths.