Suppression of Surface Leakage Currents in InAs Avalanche Photodiodes via Sputtering of High- k Dielectric Layers

The effectiveness of a range of alternative high- ${k}$ dielectric layers as potential passivation layers for InAs avalanche photodiodes has been investigated. The suppression of surface leakage currents is investigated by analyzing the current–voltage performance of differently sized mesa diodes passivated with each oxide layer. Three potential passivation layers, such as ZnO, Al ₂ O ₃ , and MgO, have been identified, all of which enables the suppression of surface leakage in smaller sized devices of a radius of $50~\mu \text{m}$ and at lower temperatures of 175 K compared to a reference SU8 device. The influence of repeated temperature cycling on these layers has also been investigated with Al ₂ O ₃ passivated devices, exhibiting no change in performance after multiple cooling and heating cycles.