Low-temperature growth of high-conductivity graphene/copper structures: applications in energy-efficient graphene photodetectors

Abstract

This study demonstrates a simple and effective two-step strategy for synthesizing high-quality graphene on copper foils at a low growth temperature of 400 °C, significantly reducing the temperature required compared with conventional CVD methods. First, CO₂ laser pretreatment is applied to the copper substrate, which significantly improves surface smoothness and reduces surface oxides and particulates through localized heating. This process effectively lowers the nucleation density, thereby promoting the formation of larger graphene domains with fewer grain boundaries. Importantly, this approach addresses the common challenge of high defect density in low-temperature-synthesized graphene, enabling the production of films with excellent electrical and structural quality. The graphene/Cu hybrid structure achieves a 66.9% reduction in electrical resistance compared to pristine copper foil and demonstrates outstanding oxidation resistance. To demonstrate practical relevance, a photodetector fabricated using the low-temperature graphene exhibits a high responsivity of 666.95 mA W⁻¹ and a detectivity of 2.32 × 10¹⁰ Jones under 5 V bias and 100 W m⁻² illumination. Moreover, it maintains stable switching performance even at 0.1 V, highlighting its suitability for low-power optoelectronic and sensor applications.