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HL: Fachverband Halbleiterphysik

HL 30: Poster I

HL 30.24: Poster

Dienstag, 17. März 2020, 13:30–15:45, P3

Investigation of Poole-Frenkel-ionization in magnesium-doped AlGaN short period superlattices — •Emil Mickein¹, Anton Muhin¹, Norman Susilo¹, Luca Sulmoni¹, Martin Guttmann¹, Christian Kuhn¹, Tim Wernicke¹, and Michael Kneissl^1,2 — ¹Technische Universität Berlin, Institute of Solid State Physics, Berlin, Germany — ²Ferdinand-Braun-Institut, Leibnitz-Institut für Höchstfrequenztechnik, Berlin, Germany

UVC-transparent Al_xGa_1−xN:Mg/Al_yGa_1−yN:Mg short period superlattices (SPSL) with x,y≥ 0.6 are required for efficient light emitting diodes with emission wavelength below 280 nm. However, AlGaN:Mg layers with high aluminum mole fractions exhibit high acceptor ionization energies and consequently a poor electrical conductivity. Moreover, the electric properties of AlGaN:Mg-SPSL are not well established, especially for high Al mole fraction. In this paper the vertical conductivity (σ_V) of Al_0.71Ga_0.29N:Mg/Al_0.65Ga_0.35N:Mg-SPSLs will be investigated. By comparing LEDs with varing SPSL-thickness σ_V was extracted. The value of σ_V was found to be strongly field- and temperature-dependent and fits well to predictions made by 3D-Poole-Frenkel-effect (3D-PFE). An activation energy of 530 meV and an intertrap distance of 6 nm were extracted for the SPSL. When comparing a SPSL with an Al-content of 78 % and a SPSL with an Al-content of 65 % σ_V is increased by more than one order of magnitude, respectively.