A prototypical design of AlGaN deep ultraviolet (DUV) laser diodes (LDs) on AlN substrates employing tapered electron blocking layer is presented. Two-dimensional optoelectronic simulation predicts lasing at a target wavelength of 250 nm. Degradation of optical gain associated with spatial separation of electron and hole wave functions inside the active region may be considerably reduced in designs featuring quaternary AlInGaN barriers, by virtue of polarization charge matching. A systematic method for selection of polarization-free quaternary barrier compositions is proposed for 250 nm DUV LD designs, accompanied by a sensitivity analysis. The selection procedure presented here is readily applied to LDs and light-emitting diodes operating at other wavelengths.
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