Effects of Diffusion Barrier Layers on the Performance of Lattice-Mismatched Metamorphic In_0.83Ga_0.17As Photodetectors

In the planar-type InGaAs photodetector (PD) structure, a diffusion barrier has the effect of modifying the zinc diffusion profile in the interface between the cap and the absorption layer to improve device performance. In this work, an n-type In0.83Ga0.17As diffusion barrier layer (DBL) is employed between the In0.83Al0.17As cap layer and the low-doped In0.83Ga0.17As absorption layer of a lattice-mismatched metamorphic In0.83Ga0.17As PD. The device performance of the In0.83Ga0.17As PDs in terms of dark current, quantum efficiency, and capacitance were simulated and compared to experimental results. The effects of the thickness and doping concentration of the DBL on PD performance were analyzed and shown to be optimized at both 300 K and 200 K. Based on the simulation results, the electron concentration of the DBL is recommended to be 3×1016–5×1016 cm−3 and a thickness of 0.1 μm is suggested.