Active Region Cascading for Improved Performance in InAs–GaSb Superlattice LEDs

Cascading of active regions in InAs-GaSb superlattice light-emitting diodes (LEDs) grown by molecular beam epitaxy is demonstrated as an effective means of increasing optical emission. Devices were fabricated into 120 x 120 mum
²
mesas to demonstrate suitability for high resolution projection systems. Devices with 1, 4, 8, and 16 stages were designed for midwave infrared emission at 3.8 mum operating at 77 K, and quasi-continuous-wave output powers in excess of 900 muW from a 16-stage LED have been demonstrated. External quantum efficiency is shown to improve substantially with cascading, approaching 10% for a 16-stage device.