Innovative all-silicon based a-SiNx:O/c-Si heterostructure solar-blind photodetector with both high responsivity and fast response speed

Hengping Dong,Huafeng Yang,Zhongyuan Ma,Xinfan Huang,Wei Li,Kunji Chen,Jun Xu,Linwei Yu

doi:10.1063/5.0071602

Hengping Dong, Huafeng Yang + Show 6 more

Open Access

https://doi.org/10.1063/5.0071602

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Abstract

The photoresponsivity and response speed are two key figures of merit for the photodetector (PD). According to the previous reports, there is an inherent contradiction between high photoresponsivity and fast response speed in normal photoconductive-type PDs. Facing the challenge of coordinating this inherent contradiction, we propose an innovative design idea, which employs a luminescent wide-bandgap (WBG) amorphous oxynitride (a-SiNx:O) film as an absorption layer combining with monocrystalline silicon (c-Si) as a carrier transport layer, to construct an all-silicon based a-SiNx:O/c-Si heterostructure photoconductive-type solar-blind photodetector (SBPD). Benefiting from the built-in electric field in the a-SiNx:O/c-Si heterojunction and good passivation at the SiNx:O/Si interface, the photogenerated carriers in the a-SiNx:O layer can be injected into the c-Si layer, which separates the carrier transport process from the carrier photogeneration/recombination process in the different layers. Since the transport process of injected carriers in the c-Si layer is much faster than their recombination process, the detector yields a large photoconductive gain, thus overcoming the above-mentioned inherent contradiction in normal photoconductive-type PDs, where both the defect-related carrier photogeneration/recombination process and carrier transport process occur in the same active layer. The designed SBPDs exhibit highlighted performance with both the high responsivity (R) of 4 × 103 A/W at 225 nm and the fast response speed of 4.3 µs. Compared to most other WBG semiconductor SBPDs, e.g., AlxGa1−xN, MgxZn1−xO, Ga2O3, and diamond, the advantages of the a-SiNx:O/c-Si heterostructure SBPD lie not only in adopting economic Si-based materials but also in manufacturing processes compatible with mature CMOS technology, thereby rendering it preferable for the development of cost-effective large-area SBPD arrays.

Highlights

Solar-blind photodetectors (SBPDs), sensitive to the ultraviolet (UV) light of wavelength in the range of 200–280 nm, have recently aroused the interest of researchers owing to their wide applications in both civil and military fields, such as fire prevention, air purification, ozone monitoring, missile warning, space communication, and so on.1 Si, usually regarded as the backbone of microelectronic industry, is deemed to be a principal material for commercialPD products.2 Due to the limitation of its sensitivity to low-energy radiation because of the narrow bandgap, the application of the Si material in solar-blind UV PDs is not as prevalent as its visible or near infrared counterparts
Facing the challenge of coordinating this inherent contradiction, we propose an innovative design idea, which employs a luminescent wide-bandgap (WBG) amorphous oxynitride (a-SiNx:O) film as an absorption layer combining with monocrystalline silicon (c-Si) as a carrier transport layer, to construct an all-silicon based a-SiNx:O/c-Si heterostructure photoconductive-type solar-blind photodetector (SBPD)
Since the transport process of injected carriers in the c-Si layer is much faster than their recombination process, the detector yields a large photoconductive gain, overcoming the above-mentioned inherent contradiction in normal photoconductive-type PDs, where both the defect-related carrier photogeneration/recombination process and carrier transport process occur in the same active layer

Summary

Introduction

Solar-blind photodetectors (SBPDs), sensitive to the ultraviolet (UV) light of wavelength in the range of 200–280 nm, have recently aroused the interest of researchers owing to their wide applications in both civil and military fields, such as fire prevention, air purification, ozone monitoring, missile warning, space communication, and so on.1 Si, usually regarded as the backbone of microelectronic industry, is deemed to be a principal material for commercialPD products.2 Due to the limitation of its sensitivity to low-energy radiation because of the narrow bandgap, the application of the Si material in solar-blind UV PDs is not as prevalent as its visible or near infrared counterparts.

Results

Conclusion