## 3 Results and Discussion  
Table 1 lists the values of \(V_{\text{f}}\), the EL peak wavelength, the EL full width at half maximum (FWHM), and the LOP at a value of \(I_{\text{f}}\) of 100 mA, all measured before and after filling the silicone into the samples S1-S3 as the encapsulant and attaching a quartz glass as the cover. Notably, S4 was a reference sample prepared without encapsulating silicone, but featuring a covering quartz glass. All the EL spectra featured a near-constant peak wavelength of approximately 311 nm and an EL FWHM of approximately 9.5 nm. Furthermore, the average variations in the values of \(V_{\text{f}}\) were all less than 1%. In contrast, significant enhancements in the LOP occurred for samples S2 and S3 after encapsulation: 7 and 5% (tolerances: \(\pm 1\%\)), respectively. We attribute this behavior to lower degrees of total internal reflection (TIR) after decreasing the refractive index (\(n\)) gap between the UVB-LED chip (sapphire; \(n=1.82\)) and air (\(n=1\)) by encapsulating silicone within the gap [26]. Moreover, compared with the LOP for sample S4, the LOPs for samples S1-S3 after encapsulation were enhanced by 3.2, 13.8, and 11.7%, respectively, due directly to the \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Before Processing**} & \multicolumn{4}{c}{**After Processing**} & \multicolumn{1}{c}{**LOP**} \\ \cline{2-10}
**Package** & \(V_{\text{f}}\) **(V)** & **Weale** & **FWHM** & **LOP** & **V\({}_{\text{f}}\) **(V)** & **Weale** & **FWHM** & **LOP** & **Enhancement** \\  & & **(nm)** & **(nm)** & **(mW)** & & **(nm)** & **(nm)** & **(mW)** & **Ratio** \\ \hline S1 & 5.55 & 311 & 9.6 & 6.35 & 5.58 & 311 & 9.4 & 6.19 & 0.97 \\ S2 & 5.53 & 311.4 & 9.6 & 6.37 & 5.51 & 311 & 9.6 & 6.83 & 1.07 \\ S3 & 5.58 & 311 & 9.4 & 6.78 & 5.54 & 310.9 & 9.5 & 7.13 & 1.05 \\ S4 & 5.53 & 310.9 & 9.5 & 6.63 & 5.51 & 311 & 9.5 & 6.23 & 0.94 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Variations in the values of \(V_{\text{f}}\), the EL peak wavelength, the EL FWHM, and the LOP of samples S1–S4 measured at 100 mA, before and after encapsulating with silicone and covering with quartz glass. Figure 2: Structural diagrams of the packaging structures (samples S1–S4). The yellow part is the DPC film with an Au coating over the surface; the blue part is the LED chip; the green part is the encapsulated silicone; the pink part is the quartz glass; and the black part is the AlN ceramic material. influence of the encapsulating silicone. Thus, the LEEs of the UVB-LEDs were improved after filling silicone inside the AlN-DPC LFs of the proposed packaging structures. Figure 3 displays the relative LOPs of the packaging samples over time; the values were normalized to the initial value. After operation with an aging time of 200 h, the relative LOPs of samples S1-S4 decreased to 70, 67.5, 71.4, and 70.9% of their initial values, respectively. Although the rates of degradation of samples S1, S3, and S4 were not obviously different, that of sample S2 was slightly faster during the 200 h of aging. Furthermore, the rates of degradation of samples S2 and S3 (\(-19.6\) and \(-17.5\)%, respectively) were faster than those of samples S1 (\(-12.3\)%) and S4 (\(-9.7\)%) during operation between 200 and 700 h. Interestingly, cracks were not present in the encapsulated silicone of samples S1-S3, observed using a microscope, prior to an aging time of 700 h. Cracks did appear, however, in the encapsulated silicone of samples S1-S3 after operation with an aging time of 1500 h. Furthermore, in comparison with reference sample S4, cracks were evident in photographs of samples S1-S3 after aging for 3500 h (Figure 4). Thus, the different rates of degradation of the UVB-LEDs, when silicone was introduced as the encapsulating material, were not obviously correlated with the phenomena of cracks appearing in the silicone during long-term operation.