Effects of Diffusion Barrier Layers on the Performance of Lattice-Mismatched Metamorphic In[sub.0.83]Ga[sub.0.17]As 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 In[sub.0.83]Ga[sub.0.17]As diffusion barrier layer (DBL) is employed between the In[sub.0.83]Al[sub.0.17]As cap layer and the low-doped In[sub.0.83]Ga[sub.0.17]As absorption layer of a lattice-mismatched metamorphic In[sub.0.83]Ga[sub.0.17]As PD. The device performance of the In[sub.0.83]Ga[sub.0.17]As 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 3×10[sup.16]–5×10[sup.16] cm[sup.−3] and a thickness of 0.1 μm is suggested.