Abstract
GeSn/Ge p-i-n photodetectors with practical Ge0.964Sn0.036 active layers are theoretically investigated. First, we calculated the electronic band parameters for the heterointerfaces between strained Ge1−xSnx and relaxed (001)-oriented Ge. The carrier transport in a p-i-n photodiode built on a ten-period Ge0.964Sn0.036/Ge multiple quantum well absorber was then analyzed and numerically simulated within the Tsu−Esaki formalism by self-consistently solving the Schrödinger and Poisson equations, coupled to the kinetic rate equations. Photodetection up to a 2.1 μm cut-off wavelength is achieved. High responsivities of 0.62 A W−1 and 0.71 A W−1 were obtained under a reverse bias voltage of −3 V at peak wavelengths of 1550 nm and 1781 nm, respectively. Even for this low Sn-fraction, it is found that the photodetector quantum efficiency (49%@1.55 μm) is higher than those of comparable pure-Ge devices at room temperature. Detectivity of 3.8 × 1010 cm Hz1/2 W−1 and 7.9 × 1010 cm Hz1/2 W−1 at −1 V and −0.5 V, respectively, is achievable at room temperature for a 1550 nm wavelength peak of responsivity. This work represents a step forward in developing GeSn/Ge based infrared photodetectors.
Highlights
In recent years, there has been increasing effort toward the development and realisation of group IV semiconductor optoelectronic devices, recently encouraged by their possible heterogeneous integration with CMOS technology on silicon on insulator (SOI) and germanium on insulator (GeOI) substrates
The carrier transport in a p-i-n photodiode built on a ten-period Ge0.964Sn0.036/Ge multiple quantum well absorber was analyzed and numerically simulated within the Tsu−Esaki formalism by self-consistently solving the Schrödinger and Poisson equations, coupled to the kinetic rate equations
In order to understand the evolution of the dark current with the bias voltage, it is necessary to determine the respective influence of each component originating from the different considered mechanisms that include the conduction, diffusion, recombination and thermally activated tunnel currents
Summary
Faculty of Science and Art KKU Mahail Assir, King Kaled University, Saudi Arabia. on insulator (SOI) and germanium on insulator (GeOI) substrates. There have been reports on GeSn p-i-n photodetectors with small Sn content for full telecommunication spectral range applications [11]. These results show that adding Sn in a p-i-n Ge photodiode matrix increases the responsivity of the detector in the telecom wavelength range and extends the cut-off wavelength beyond 1.7 μm [12,13,14]. The detection wavelength of GeSn p-i-n photodetectors fabricated on Ge substrate with Sn contents up to 3.6% in the active layer has recently reached 1.95 μm [15]. The room temperature performance is presented and discussed in terms of responsivity and detectivity
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