A. Muhin¹, M. Guttmann¹, C. Kuhn¹, E. Mickein¹, J.R. Aparici¹, E. Ziffer¹, N. Susilo¹, L. Sulmoni¹, T. Wernicke¹, and M. Kneissl^1,2

Published in:

Appl. Phys. Lett., vol. 117, no. 25, pp. 252101, doi:10.1063/5.0027336 (2020).

Abstract:

Mg-doped AlGaN short-period superlattices with a high aluminum mole fraction are promising to fabricate highly efficient deep UV light emitting diodes. We present a robust and easy-to-implement experimental method for quantification of the vertical component of the anisotropic short-period superlattice conductivity based on current-voltage characteristics of devices with varying short-period superlattice thicknesses. In particular, the vertical conductivity of Al_0.71Ga_0.29N/Al_0.65Ga_0.35N:Mg short-period superlattices is investigated and found to be strongly affected by the temperature and by the applied electric field. At room temperature, the vertical conductivity varies between 5.5×10^-7Ω^-1cm^-1 at 0.05 MV cm^-1 and 6.7×10^-5Ω^-1cm^-1 at 0.98 MV cm^-1 and increases by almost two orders of magnitude when the temperature increases up to 100°C. This behavior is in very good agreement with simulations based on a 3D-Poole-Frenkel model. In addition, the zero-field ionization energy and the inter-trap distance of the Mg acceptors in the AlGaN short-period superlattices were determined to be 510±20 meV and 5.1±0.3 nm, respectively.

Topics:

Ultrawide Bandgap Semiconductors; Semiconductors; Current-voltage characteristic; Superlattices; Light emitting diodes

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