Abstract
To develop and design an environmentally friendly, low-cost shortwave infrared (SWIR) photodetector (PD) material and extend the optical response cutoff wavelengths of existing silicon photodetectors beyond 1100 nm, high-performance silicon-compatible Mg2Si/Si PDs are required. First, the structural model of the Mg2Si/Si heterojunction was established using the Silvaco Atlas module. Second, the effects of the doping concentrations of Mg2Si and Si on the photoelectric properties of the Mg2Si/Si heterojunction PD, including the energy band, breakdown voltage, dark current, forward conduction voltage, external quantum efficiency (EQE), responsivity, noise equivalent power (NEP), detectivity, on/off ratio, response time, and recovery time, were simulated. At different doping concentrations, the heterojunction energy band shifted, and a peak barrier appeared at the conduction band of the Mg2Si/Si heterojunction interface. When the doping concentrations of Si and Mg2Si layer were 1017, and 1016 cm−3, respectively, the Mg2Si/Si heterojunction PD could obtain optimal photoelectric properties. Under these conditions, the maximum EQE was 70.68% at 800 nm, the maximum responsivity was 0.51 A/W at 1000 nm, the minimum NEP was 7.07 × 10−11 WHz–1/2 at 1000 nm, the maximum detectivity was 1.4 × 1010 Jones at 1000 nm, and the maximum on/off ratio was 141.45 at 1000 nm. The simulation and optimization result also showed that the Mg2Si/Si heterojunction PD could be used for visible and SWIR photodetection in the wavelength range from 400 to 1500 nm. The results also provide technical support for the future preparation of eco-friendly heterojunction photodetectors.
Highlights
Photodetector (PD) material and extend the optical response cutoff wavelengths of existing silicon photodetectors beyond 1100 nm, high-performance silicon-compatible Mg2 Si/Si PDs are required
The results provide technical support for the future preparation of eco-friendly heterojunction photodetectors
Ref. [21] reported that holes, the carriers generated by absorbing light increased, the photocurrent was improved the external quantum efficiency (EQE) of the InSb/Si heterojunction PD was 25%
Summary
At present, infrared photodetectors are mainly composed of HgCdTe, InSb, InGaAs, and other materials, but these materials are highly toxic and have low abundance in the. Semiconductor silicides (Mg2 Si, Ca2 Si, BaSi2 , CrSi2 , and FeSi2 ) and related germanium compounds are environmentally friendly and have high absorption coefficients and narrow band gaps [2,3] These materials may be suitable alternatives to the current SWIR sensors of toxic materials, their current performances are low. We established the model structure of the Mg2 Si/Si heterojunction PD and studied the effects of the Mg2 Si and Si doping concentrations on the photoelectric properties of the Mg2 Si/Si heterojunction PD, including the energy band, reverse breakdown voltage, dark current, forward conduction voltage, external quantum efficiency (EQE), responsivity, noise equivalent power (NEP), detectivity, on/off ratio, response time, and recovery time The results of these photoelectric properties were analyzed and summarized, and suitable doping concentrations of Mg2 Si and Si were obtained, which were 1016 cm−3 , and 1017 cm−3 , respectively. The proposed simulation method could reduce the design cost and shorten the development cycle for PD devices
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