Effects of ultraviolet-assisted photo-electrochemical (PEC) etching current densities (J = 20, 40, 80, and 160 mA/cm 2 ) towards structural, physical, and optical properties of aluminium indium gallium nitride (AlInGaN) semiconductors as well as corresponding schematized mechanism were studied and discussed. Formation of porous AlInGaN semiconductors at J lower than 80 mA/cm 2 has led to the acquisition of larger lattice parameters c and a, out-of-plane strain, in-plane strain, and hydrostatic

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... train as compared to the non-porous semiconductor, owing to the generation of more vacancy-type defects in the porous AlInGaN semiconductors. For the porous semiconductor formed at J greater than 80 mA/cm 2 , the etching was affected by a limited mass transport of electrons and holes for anodic oxidation and cathodic reduction. According to the band gap (E g ) and Urbach energy (U E ) determined from photoluminescence (PL) shift and UV-Vis absorption measurement, the vacancy-type defects were revealed as the radiative localized states that led to the enhancement in PL peak intensity. The acquisition of a lower density of