Work

Stacked Si/GaN tunnel junction flip-chip light-emitting diodes with improved external quantum efficiency

Year: 2026

Type: article

Abstract: • Fabricated a vertically stacked Si/GaN TJ FC LED using transfer-printed crystalline Si nanomembrane with a continuous heterointerface. • Enhanced interband tunneling improved hole injection and carrier balance in InGaN/GaN MQWs. • High Si transmittance (∼86%) and Al reflectivity (∼85%) enabled efficient top-side light extraction. • Achieved 33.3% higher peak EQE and 31.4% reduced droop at 40 A/cm 2 vs reference LED. • Demonstrated an effective strategy for high-efficiency, high-brightness micro-LEDs. A vertically stacked Si/GaN tunnel junction flip-chip light-emitting diodes (TJ FC LED) were demonstrated through stacking a crystalline Si nanomembrane (Si NM) onto a GaN epi-layer. The resulting stacked Si/GaN heterostructure exhibited a continuous interface with an ultrathin amorphous interlayer accommodating the Si/GaN lattice mismatch. Optical analysis revealed high transmittance (∼86%) of Si NM and strong reflectivity (∼ 85%) from Al current-spreading layer, enabling efficient top-side light extraction. Band structure simulations confirmed enhanced interband tunneling across the Si/GaN interface, leading to improved hole injection and more balanced carrier distribution in the InGaN/GaN multiple quantum wells. Compared with a reference LED, the TJ FC LED exhibited significantly enhanced electroluminescence intensity, achieving 1.68 × 10 16 more emitted photons, a 33.3% higher peak external quantum efficiency, and a 31.4% reduction in efficiency droop at 40 A/cm 2 . These results demonstrate the effectiveness of the TJ and FC architecture in simultaneously enhancing carrier transport and light extraction, offering a promising pathway toward high-efficiency and high-brightness micro-LEDs.

Source: Results in Physics

DOI: 10.1016/j.rinp.2026.108623

Author: Kwangeun Kim

Institution: Korea Aerospace University

Language: English

Topic: GaN-based semiconductor devices and materials

Subfield: Condensed Matter Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,920

Funders: National Research Foundation of Korea, Ministry of Science and ICT, South Korea