High Performance Ingaas/Inalas Avalanche Photodiodes Using Carbon-Doped P-Inalas as the Charge Layer

Abstract

An avalanche photodiode (APD) is a widely used device, especially in weak light detection systems like fiber optic detection. InAlAs is suitable for the fabrication of multiplication and charge layers, and has drawn more and more attention due to its low excess noise factor and large bandgap. However, the use of InAlAs as a charge layer also poses significant problems, especially in the implementation of p-type doping. In this work, by adjusting the growth parameters, we achieved high-quality carbon-doped p-InAlAs epitaxial layer. Moreover, four InGaAs/InAlAs avalanche photodiodes with a structure of a separated i-InGaAs absorption layer, p-InAlGaAs grade layer, p-InAlAs charge layer, and i-InAlAs multiplication layer (SAGCM) were prepared by tailoring the doping concentration of the p-InAlAs charge layer. When the doping concentration of the p-InAlAs charge layer is 4.13×1017 cm-3, the fabricated photodiode exhibits avalanche multiplication characteristics. The device at a doping concentration of 4.13×1017cm-3 for the p-InAlAs charge layer has good photoelectric performance, with a responsivity as high as 12.19 A/W and a multiplication factor as high as 16 at 31.9 V measured at 300 K. By analyzing the electric field distribution within the device under different doping concentrations of the p-InAlAs charge layer, we believe that the key to good device performance lies in the appropriate doping concentration of the p-InAlAs charge layer. Our work provides some ideas for realizing an APD device with high performance and low breakdown voltage.

Keywords: Avalanche photodiodes, InAlAs, Electric field distribution, Carbon doping