Role of a thin interfacial oxide layer and optimized electrodes in improving the design of a Graphene/n-Si MSM photodetector

In this paper, the role of a thin interfacial oxide layerin reducing the dark current of an n-Si metal semiconductor metal (MSM) ultraviolet (UV) photodetector (PD) is investigated by means of an accurate analytical model. Besides, the benefits of Graphene (Gr) monolayer as transparent electrode are investigatedin detail. An interdigitated Gr electrode (IGE) formalism is proposed to reach the dual purpose of enhancing the device absorption and improving the photogeneratedcarrierscollection. Moreover, considering the carrier loss mechanisms effect, a comprehensive comparison between the suggestedGraphene/Siliconphotodetector and the conventional photodetectors based on silver (Ag) and gold (Au) electrodes has been carried out. The obtained results prove the Gr capability in enhancing the device optical performances benefiting from its high transparency and excellentconductivity. The proposed design outperforms conventional designs using Ag and Au where a high values of responsivity (675 mA/W), detectivity (176.4 x 1010 Jones) and LDR (179.5 dB) are achieved. Graphene work function effects are also investigated. Thework function tenability, in fact, performs a key role in the control of Schottky barrier height, which can improve the device photocurrent. The model developed in this study formulates the fitness function for the NSGAII technique to pursue the optimal combination of design parameters for which the electrical and optical device performances are maximized.

Automated summary

This paper investigates the role of a thin interfacial oxide layer in reducing the dark current of an n-Si metal semiconductor metal (MSM) ultraviolet (UV) photodetector and explores the benefits of graphene monolayer as a transparent electrode. The proposed design using graphene outperforms conventional designs using silver and gold electrodes, achieving high responsivity, detectivity, and low dark current. The study also examines the effect of graphene work function on device performance.