Enhanced vertical and lateral hole transport in high aluminum-containing AlGaN for deep ultraviolet light emitters

Improved p-type conductivity is demonstrated in AlGaN:Mg superlattice (SL) cladding layers with average Al composition ∼60%. The vertical conductivity ranges from 6.6 × 10−5 S/cm at a DC current of 1 mA to ∼0.1 S/cm at 550 mA and approaches the lateral conductivity that was obtained from Hall-effect measurements. The effective acceptor activation energy (EA) in the SL was determined to be 17 meV, nearly 10× smaller than EA in homogeneous p-GaN. The devices sustain current densities of 11 kA/cm2 under DC and up to 21 kA/cm2 under pulsed operation.