Direct band gap InxGa1−xAs/Ge type II strained quantum wells for short-wave infrared p-i-n photodetector

We theoretically investigate GaAs/Ge/InGaAs as a quantum wells for the design of short-wave infrared p-i-n photodetectors in which the quantum well Ge/InGaAs is the active region. At room temperature, strained Ge/InxGa1−xAs becomes a direct band gap when In composition x is lower than 2.5% and 5% respectively. We have calculated the electronic band parameters for the heterointerface Ge/InxGa1−xAs. Then, a type-II strain GaAs/Ge/In0.35Ga0.65As/GaAs quantum wells heterostructure optimized in terms of compositions and thicknesses is studied by solving Schrödinger equation as well as the absorption coefficient (>1.5 × 104 cm−1). These computations have been used for the study of p-i-n infrared photodetectors operating at room temperature in the range 1.3-1.55 μm. The electron transport in the GaAs/Ge/In0.35Ga0.65As/GaAs multi-quantum wells-based p-i-n structure was analyzed and numerically simulated taking into account tunneling process and thermally activated transfer through the barriers mainly. The temperature dependence of dark current mechanisms and zero-bias resistance area product (R0A) have been analyzed. Extracted from current-voltage characteristics, R0A products above 3.6 ⋅ 106 Ω cm2 at 77 K were calculated, and the quantitative analysis of the J-V curves showed that the dark current density of Ge/In0.35Ga0.65As photodetector is dominated by generation-recombination processes. The suitability of the modeled photodetector is approved by its feasibility of achieving good device performance near room temperature operating at 1.55 μm. Quantum efficiency of ∼90% and responsivity ∼0.6 A/W, have been achieved.