LED Strain Management Layers Combining Superlattice and Bulk InGaN

The strain management layer is segmented into multiple discrete layers with different compositions and functions. The structure includes a buffer layer, followed by multiple quantum well layers with varying Indium concentrations (e.g., 5-15% InGaN, 15-25% InGaN, 25-35% InGaN), and interspersed barrier layers. This segmentation allows each layer to be optimized for specific purposes: the buffer layer for substrate adhesion and initial strain management, intermediate layers for gradual strain accumulation, and higher Indium concentration layers for enhanced light emission without excessive pit formation.

Different regions of the strain management layer structure have different local compositions and properties. The Indium concentration is locally varied across different quantum well layers, with lower concentrations in deeper layers and higher concentrations in upper layers. Each local region is tailored to provide optimal strain management and light emission characteristics for its specific position in the structure, preventing uniform pit formation while maintaining overall performance.

Instead of using a single thick Indium-containing layer, the structure divides the total Indium content across multiple thinner quantum well layers separated by barrier layers. Each thin layer maintains acceptable surface morphology while the cumulative effect of multiple layers provides the desired material quality and strain management. The barrier layers between quantum wells prevent pit coalescence and maintain surface integrity.

The buffer layer is deposited first to establish a stable foundation with appropriate lattice matching before subsequent Indium-containing layers are added. This preliminary action prepares the substrate to accommodate higher Indium concentrations in later layers without immediate pit formation, allowing gradual buildup of material quality while maintaining surface morphology throughout the deposition process.