Design and Analysis of 250-nm AlInN Laser Diodes on AlN Substrates Using Tapered Electron Blocking Layers

A theoretical investigation into the operation of AlInN ultraviolet laser (UV) diodes on AlN substrates is presented. 2-D optoelectronic simulation of a prototypical design predicts lasing at a target wavelength of 250 nm. Simulations indicate optical gain degradation attributable to a parasitic inversion layer, which forms as a result of polarization charge associated with homogeneous electron blocking layers. Appreciable improvement in optical gain is demonstrated in designs featuring inhomogeneous electron blocking layers, by virtue of a volumetric redistribution of polarization charge. Numerical simulations inspire confidence in AlInN as a viable alternative to AlGaN technologies for UV laser-diode operation.