MOCVD growth and characterization of 100mm diameter (Ga1-xAlx)0.5In0.5P/GaAs epitaxial materials for LED applications

High brightness visible light emitting diodes (LEDs)based on GaAlInP/GaAs are now in great demand. In order to meet the requirements for mass production with low unit cost, metalorganic chemical vapor deposition (MOCVD) is the primary deposition process for cost effective large area and multiple wafer growth of compound semiconductors. In this work, low pressure MOCVD growth and non-destructive materials characterization on 1.00 mm (4 ") wafer size epitaxial films of quaternary GaAlInP grown on GaAs substrates for LED applications-is demonstrated. The ability to scale the deposition and fabrication process from the traditionally used 50 mm (2 ") to 100 mm (4 ") will be key in further reducing costs. MOCVD system design requires that growth to be laterally uniform, abruptly switchable, and robust against variations in process parameters that can been achieved so that production of high quality and high uniformity GaAlInP films are obtained. In parallel, to this effort there is the need to develop rapid whole wafer and non-destructive mapping characterization techniques to investigate GaAlInP material properties such as sheet resistivity, film thickness, photoluminescence (PL), Fourier transform infrared (FTIR) and Raman scattering spectra for both material (or device optimization) and for the on-going qualification of material during production. Typical unformities of GaAlInP epitaxial film thickness, sheet resistivity, major PL band peak wavelength and width are 1-3%. For techniques without automatic mapping abilities, multiple point measurements and employed to obtain information over the entire wafer. Variations of these characteristic features, such as sheet resistivity, PL and Raman properties, with different Al compositions and doping are discussed in this work.