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HL: Fachverband Halbleiterphysik

HL 72: Nitrides: Devices

HL 72.3: Vortrag

Donnerstag, 23. März 2017, 10:00–10:15, POT 06

Beyond classical band offsets: Employing multiquantum barriers for electron blocking in group III-nitride devices — •Anton Muhin¹, Martin Guttmann¹, Christoph Reich¹, Konrad Bellmann¹, Johannes Enslin¹, Norman Susilo¹, Luca Sulmoni¹, Tim Wernicke¹ und Michael Kneissl^1,2 — ¹Technische Universität Berlin , Institute of Solid State Physics — ²Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin

Electron leakage current is one of the major loss mechanisms in AlGaN-based light emitting devices (UV LEDs). This can be reduced by inserting a layer with a larger band gap into the heterostructure, an electron blocking layer (EBL), with a conduction band offset of typically 0.3-0.8 eV. By stocking multiple EBLs on a nanometer scale, an additional virtual barrier (VB) can be created by a so-called multiquantum barrier (MQB) structure. Numerical calculations were performed of AlGaN-MQBs in order to quantify the VB, the optimal structure parameters and their robustness to fluctuations. Polarization fields and the band profile have been modeled by solving the Poisson‘s equation. Transfer matrix method and the Esaki-Tsu current formula were applied to compute the reflection probabilities and the current-voltage-characteristics, respectively. The simulations show an increase of the effective barrier height of 66% when employing on optimized Al_0.2Ga_0.8N/GaN-MQB compared to a Al_0.2Ga_0.8N EBL of the same thickness on GaN. Approaches to verify the VB experimentally will be discussed in this talk.