## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Authors** & **CMOS Technology** & **Photodiode Structure** & **Maximum Quantum Efficiency** & **Active Area** & **Dark Current** & **Ref.** \\ \hline [PERSON] and D. & 0.35 \(\upmu\)m & n-well/p-substrate & 63\% (550 nm) & 100 \(\times\) 100 \(\upmu\)m\({}^{2}\) & 4.5 fA & [11] \\ \hline [PERSON] and R. & 0.35 \(\upmu\)m & n+/p-substrate & 85\% (650 nm) & non defined & non defined & [26] \\ [PERSON] & 0.7 \(\upmu\)m & n+/p-substrate & \(\approx\)48\% (620 nm) & 100 \(\times\) 100 \(\upmu\)m\({}^{2}\) & 144 fA & [1] \\ \hline [PERSON] & 0.7 \(\upmu\)m & p+/n-well & \(\approx\)40\% (480 nm) & 100 \(\times\) 100 \(\upmu\)m\({}^{2}\) & 4.390 pA & [1] \\ \hline [PERSON] & 0.7 \(\upmu\)m & n+/p-substrate & non defined & 100 \(\times\) 100 \(\upmu\)m\({}^{2}\) & 9.6 fA & [27] \\ \hline [PERSON] et al. & 0.18 \(\upmu\)m & n+/p-substrate & 22\% (500 nm) & 4 \(\times\) 4 \(\upmu\)m\({}^{2}\) & 2.4 fA & [28] \\ \hline [PERSON] et al. & 0.18 \(\upmu\)m & \
\begin{tabular}{c} Typical photodiode \\ (junction non specified) \\ \end{tabular} & \(\approx\)73\% (700 nm) & non defined & non defined & [29] \\ \hline  & 0.18 \(\upmu\)m &
\begin{tabular}{c} n+/p-substrate \\ \end{tabular} & 90\% (700 nm) & & 3701 fA \\ \cline{2-6}  & 0.18 \(\upmu\)m & p+/n-well & 80\% (800 nm) & & 1933 fA \\ \cline{2-6}  & & n-well/p-substrate & 65\% (850 nm) & & 1653 \\ \cline{2-6}  & 0.35 \(\upmu\)m & n+/p-substrate & 97\% (820 nm) & & 1840 fA \\ \cline{2-6}  & & p+/n-well & 82\% (820 nm) & & 2179 fA \\ \cline{2-6}  & & n-well/p-substrate & 60\% (850 nm) & & 675 fA \\ \cline{2-6}  & 0.7 \(\upmu\)m & n+/p-substrate & 80\% (720 nm) & & 4164 fA \\ \cline{2-6}  & & p+/n-well & 30\% (850 nm) & & 2205 fA \\ \cline{2-6}  & & n-well/p-substrate & 25\% (850 nm) & & 802 fA \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Quantum efficiency and dark current values for different technologies and photodiodes’ structures in the literature. specifying the p-n junction, has a similar behavior. This is the same for the photodiode presented by [PERSON] et al. [28], which shows a lower quantum efficiency, but it is at 500 nm. The simulation of the n+/p-substrate photodiode in the 0.35 \(\upmu\)m technology reported in this work presents a quantum efficiency maximum of 97%, which similarly corresponds to the same maximum reached by [PERSON] and [PERSON] [26]. However, the efficiency peaks were reached in different regions, as the current work reports the peak near the infrared range (800 nm) and [PERSON] and [PERSON] in the visible range (650 nm). The simulation of the n-well/p-substrate 0.35 \(\upmu\)m photodiode presents similar values of quantum efficiency maximum but occurs in different regions as those reported in the literature. The n+/p-substrate 0.7 \(\upmu\)m photodiode is characterized by a lower quantum efficiency, with a maximum value of 80%, different from the maximum values reported in the literature, but in the same regions of the optical spectrum. The n+/p-substrate photodiode simulated in the 0.7 \(\upmu\)m technology also presents a significant difference in the quantum efficiency peak value in relation to the n+/p-substrate photodiode reported by [PERSON] et al. [1], being significantly higher in the simulation (80% vs. 48%). Once again, this difference is explained by the presence, in the photodiode experimentally characterized and reported by [PERSON] et al. [1], of the oxide layers over the photodiode active area, which have characteristic reflectance spectra, while it is only included the p-n junction in the simulations. These oxide layers contribute to the increase of the reflectance of the photodiode surface, decreasing its quantum efficiency. Such effect could be removed experimentally by adding anti-reflection coatings. The simulated n+/p-substrate 0.7 \(\upmu\)m photodiode was also compared with similar junction photodiodes reported in the literature by [PERSON] et al.