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In this Letter, the electron-blocking-layer (EBL)-free AlGaN ultraviolet (UV) light-emitting diodes (LEDs) using a strip-in-a-barrier structure have been proposed. The quantum barrier (QB) structures are systematically engineered by integrating a 1 nm intrinsic ${\mathrm{A}\mathrm{l}}_x{\mathrm{G}\mathrm{a}}_{(1-<\#comment/>x)}\mathrm{N}$strip into the middle of QBs. The resulted structures exhibit significantly reduced electron leakage and improved hole injection into the active region, thus generating higher carrier radiative recombination. Our study shows that the proposed structure improves radiative recombination by $\sim <\#comment/>220\mathrm{\%<\#comment/>}$, reduces electron leakage by $\sim <\#comment/>11$times, and enhances optical power by $\sim <\#comment/>225\mathrm{\%<\#comment/>}$at 60 mA current injection compared to a conventional AlGaN EBL LED structure. Moreover, the EBL-free strip-in-a-barrier UV LED records the maximum internal quantum efficiency (IQE) of $\sim <\#comment/>61.5\mathrm{\%<\#comment/>}$which is $\sim <\#comment/>72\mathrm{\%<\#comment/>}$higher, and IQE droop is $\sim <\#comment/>12.4\mathrm{\%<\#comment/>}$, which is $\sim <\#comment/>333\mathrm{\%<\#comment/>}$less compared to the conventional AlGaN EBL LED structure at $\sim <\#comment/>284.5\mathrm{n}\mathrm{m}$wavelength. Hence, the proposed EBL-free AlGaN LED is the potential solution to enhance the optical power and produce highly efficient UV emitters. 

In this paper, deep ultraviolet AlGaN light-emitting diodes (LEDs) with a novel double-sided step graded superlattice (DSGS) electron blocking layer (EBL) instead of a conventional EBL have been proposed for $\sim <\#comment/>254\mathrm{n}\mathrm{m}$wavelength emission. The enhanced carrier transport in the DSGS structure results in reduced electron leakage into the $p$-region, improved hole activation and hole injection, and enhanced output power and external quantum efficiency. The calculations show that output power of the DSGS structure is $\sim <\#comment/>3.56$times higher and electron leakage is $\sim <\#comment/>12$times lower, compared to the conventional structure. Moreover, the efficiency droop at 60 mA in the DSGS LED was found to be $\sim <\#comment/>9.1\mathrm{\%<\#comment/>}$, which is $\sim <\#comment/>4.5$times lower than the regular LED structure.