Effect of ITO/SiO${}_2$ double-layer film thickness on the optoelectronic performance of metal-doped ITO near-UV LED

In order to optimize the optoelectronic performance based on metal-doped ITO LED, the effect of the thickness of the ITO/SiO${}_2$ double-layer film in metal-doped ITO LED is investigated in this paper. Al-doped ITO films with thicknesses of 50 nm, 70 nm, and 110 nm were designed and prepared on the UV LED epitaxial wafer with a peak wavelength of 393 nm, and a 90 nm SiO${}_2$ passivation layer was prepared on its surface to form Al-doped ITO/SiO${}_2$ double-layer film of 140 nm, 160 nm and 200 nm on the surface of the LED. At the same time, ITO/SiO${}_2$ double-layer films of the above three thicknesses formed by undoped ITO films with SiO${}_2$ passivation layers were prepared on the slides. The photovoltaic properties of the prepared LED and the transmittance and square resistance of the ITO/SiO${}_2$ double-layer film were measured. The experimental data show that the LED with a 200 nm Al-doped ITO/SiO${}_2$ double-layer film has 13.8% and 26% enhanced optical power compared to the LED with 140 nm and 160 nm Al-doped ITO/SiO${}_2$ double-layer film system, respectively, and it has the lowest operating voltage. By comparing the optical power of LED with metal-doped ITO to the light transmittance of an undoped ITO/SiO${}_2$ double-layer film, we found that the effect of metal doping is related to the thickness of the ITO double-layer film, and there is a negative correlation between the two in a specific range.