Polarization-Enhanced p-AlGaN Superlattice Optimization for GUV LED

AlGaN germicidal ultraviolet (GUV) light emitting diodes (LEDs) are one of the most promising disinfection technologies in fighting the COVID-19 pandemic; however, GUV LEDs are still lacking in efficiency due to low p-type doping efficiency in p-AlGaN. The most successful approach for producing conductive p-type AlGaN is the implementation of a polarization-enhanced short period Al
$_{\mathbf {x}}$
Ga
$_{\mathbf {1-}\mathbf {x}}$
N/Al
$_{\mathbf {y}}$
Ga
$_{\mathbf {1-}\mathbf {y}}$
N superlattice (SL) structure, which enhances hole injection and reduces device operating voltage. In this report, we investigated different aspects of the superlattice including the Al
$_{\mathbf {x}}$
Ga
$_{\mathbf {1-}\mathbf {x}}$
N and Al
$_{\mathbf {y}}$
Ga
$_{\mathbf {1-}\mathbf {y}}$
N alloy constituent compositions,
${x}$
and
${y}$
, period thickness, total thickness, and Mg dopant concentration in terms of LED performance as well as electrical, optical, and morphological characteristics. The polarization-enhanced p-type doping in the AlGaN superlattice was also investigated computationally, giving excellent agreement with experimental results. Highly efficient UVC LEDs (279 nm) with EQE of 2% at 5 A/cm
²
were demonstrated. A maximum output power of 5.5 mW (56 mW/mm
²
) was achieved at 100 mA.