Suppression of indium clustering and quantum confined stark effect of InGaN LED on Silicon (111)

摘要

Optical properties of InGaN/GaN multi-quantum-well (MQWs) grown on sapphire and on Si(111) are reported. The tensilestrain in the MQW on Si is shown to be beneficial for indium incorporation and Quantum-confined Stark Effect reductionin the multi-quantum wells. Raman spectroscopy reveals compressive strains of -0.107% in MQW on sapphire and tensilestrain of +0.088% in MQW on Si. Temperature-dependent photoluminescence shows in MQW on sapphire a strong (30meV peak-to-peak) S-shaped wavelength shift with decreasing temperature (6 K to 300K), whereas MQW on Siluminescence wavelength is stable and red-shifts monotonically. Micro-photoluminescence mapping over 200 by 200 μm2shows the emission wavelength spatial uniformity of MQW on Si is 2.6 times higher than MQW on sapphire, possibly dueto a more uniform indium incorporation in the multi-quantum-wells as a result of the tensile strain in MQW on Si. Apositive correlation between emission energy and intensity is observed in MQW on sapphire but not in those on Si. Despitethe lower crystal quality of MQW on Si revealed by atomic force microscopy, it exhibits a higher internal quantumefficiency (IQE) than MQW on sapphire from 6 K to 250 K, and equalizes at 300 K. Overall, MQW on Si exhibits a highIQE, higher wavelength spatial uniformity and temperature stability, while providing a much more scalable platform thanMQW on sapphire for next generation integrated photonics.