Near-unity quantum efficiency of self-powered broadband photovoltaic black Si photodetectors with passivated Schottky junction

• Main Authors: Park, Hyunjung, Kim, You Jin, Kim, Munho
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2025
• Subjects: Engineering; Silicon; Solar cell
• Online Access: https://hdl.handle.net/10356/182108
• Institution: Nanyang Technological University

This study reports an effective chlorine (Cl2) plasma technique to passivate black Si surfaces, leading to high-responsivity self-powered broadband black silicon (Si) Schottky photodetectors and solar cells. Although black Si has gathered great attention for its excellent light absorption property, its application to optoelectronic devices has been mainly limited by a low carrier lifetime and high recombination rate originating from the nanotexturing process. We propose a simple Cl2 plasma technique to enhance the Schottky junction between black Si and graphene. The effective carrier lifetime is increased from 6.5 to 16.7 μs, leading to significant enhancement of device performance (i.e., responsivity from 0.676 to 409 mA W−1 and photo-to-dark current ratio from 1.10 to 3788 at 532 nm under self-powered mode, reduced dark current density from 5.96 to 1.00 µA cm−1, and improved photoconversion efficiency from 0.05% to 2.33%). These results highlight the high potential of Cl2 plasma as an effective passivation technique, paving the way for advancements in black semiconductor devices. Furthermore, the dual-function advantages of high-quality surface passivation and excellent light absorption properties make it an attractive and efficient scheme, particularly for optoelectronic devices.