Using Atomic Force Microscopy to Control and Enhance Structural and Optical Properties of GaN-based Light Emitting Diodes Grown by MOCVD (AN80)

Red and yellow light emitting diodes (LEDs) fabricated from compound semiconductors (GaP and InGaAlP) have long been used in many display applications from automobiles to microwave ovens. The benefit offered by GaN-based structures is the extension of these devices into applications that require white light, by adding the blue/green components. LED emission is much more efficient than incandescent light generation. LEDs are also more reliable and have a longer life than incandescent sources. Some of the optical applications of blue/green LEDs and lasers include: full color display for computers and high definition television, airborne submarine surveillance systems, traffic lights, currency detectors, sanitation devices, and ultraviolet emitters. This application note exemplifies the use of atomic force microscopy (AFM) to investigating and optimizing the surface morphology of GaN-based LED constituent layers (i.e. sapphire substrate, n-type layer, active region, p-type layer) with direct implications on the structural and optical properties of such devices. The data presented herein originates from metal organic chemical vapor deposition (MOCVD) grown samples, which are part of the GaN-based LED process development research programs developed at Veeco TurboDisc® Operations in
Somerset, NJ.