Performance optimization of resonant cavity enhanced n-GaAs homojunction far-infrared detectors: A theoretical study

The n-GaAs homojunction interfacial workfunction internal photoemission (HIWIP) far-infrared (FIR) detector is investigated to improve the quantum efficiency by simulation. The main structure, the bottom mirror, and the top mirror for the resonant cavity enhanced detector are optimized step by step. Two designs of the bottom mirror are suggested and compared. One consists of a bottom contact layer and one period of undoped/doped GaAs layers; the other is composed of a bottom contact layer, an undoped GaAs layer, and a gold layer. The results show that both mirrors enhance the quantum efficiency significantly and the gold mirror seems to be a better choice if not considering the technical difficulty. Preliminary study of the top mirror is also conducted. The top mirror shows a satisfactory effect under the condition that the reflectivity of the bottom mirror is high enough. The resulting quantum efficiency can be as high as 29.0% theoretically, which is much higher than p-GaAs and Si HIWIP FIR that was ever reported.