Enhanced vertical and lateral hole transport in high aluminum-containing AlGaN for deep-UV light emitters
We report improved p-type conductivity in AlGaN:Mg superlattice (SL) cladding layers designed for deep ultraviolet light emitting devices operating at wavelengths down to 255 nm. The average Al composition in the SL was about 60%. Up to 2.1 amperes (equivalent to a current density of 21 kA/cm2) was injected vertically (perpendicular to the growth plane) through the p-type SL. The measured vertical conductivity of 6.6x10-5 S/cm in the SL is about two times greater than the conductivity of homogeneous p-Al0.6Ga0.4N. The conductivity in the lateral direction (parallel to the growth plane) was also enhanced. We attribute the improved conductivity obtained with the SL to polarization-field assisted doping. The effective acceptor activation energy in the SL was determined to be 17 meV, nearly one order of magnitude less than the acceptor activation energy in homogeneous p-type GaN.
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Cheng, B.; Choi, S.; Northrup, J. E.; Yang, Z.; Knollenberg, C.; Teepe, M. R.; Wunderer, T.; Chua, C. L.; Johnson, N. M. Enhanced vertical and lateral hole transport in high aluminum-containing AlGaN for deep-UV light emitters. Applied Physics Letters. 2013; 102 (23): 231106.
Copyright © American Institute of Physics, 2013. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters and may be found at http://link.aip.org/link/doi/10.1063/1.4809947.