Dresden 2014 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 19: Nitrides: Devices

HL 19.4: Talk

Monday, March 31, 2014, 15:45–16:00, POT 151

Al(Ga)N electron blocking heterostructure design for high injection efficient 290 nm light emitting diodes — •Martin Guttmann¹, Christoph Reich¹, Tim Kolbe^1,2, Frank Mehnke¹, Christian Kuhn¹, Jens Rass^1,2, Tim Wernicke¹, Mickael Lapeyrade², Sven Einfeldt², and Michael Kneissl^1,2 — ¹Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany — ²Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany

We report on the optical and electronic properties of AlGaN-based light emitting diodes (LEDs) with a wavelength near 290 nm using different electron blocking heterostructures. Using a conventional Al_0.7Ga_0.3N:Mg electron blocking layer (EBL) carrier injection into 290 nm LEDs proves to be challenging. A broad parasitic luminescence around 350 nm was observed, originating from electron overflow into the Mg-doped Al_0.4Ga_0.6N/Al_0.3Ga_0.7N superlattice. Our studies show that by inserting an AlN:Mg interlayer (IL) between active region and EBL, electron overflow can be prevented. This is confirmed by electroluminescence measurements and simulations. With increasing IL thickness the emission output power increases, reaches a maximum at 3 nm and remains constant for thicker IL. We present a detailed analysis of the electron and hole injection into 290 nm LEDs using simulations as well as a study of current-voltage-characteristics and the emission spectra obtained from temperature dependent and pulsed electroluminescence measurements.