Abstract
High efficiency 650 nm resonant cavity light emitting diodes (RCLEDs) with a cladding layer cavity are reported. The epitaxial structure is grown with a metal-organic chemical vapor deposition (MOCVD) system. Al 0.5Ga 0.5 As/Al As is used for the distributed Bragg reflectors (DBRs), and GaInP/AlGaInP multiple-quantum wells for the active region. Two RCLED samples have been fabricated, one with a cladding layer cavity and the other without. Experimental results show that the cladding layer cavity can improve the internal quantum efficiency effectively, so that an external quantum efficiency of 7.4% at 20 mA is reached. Meanwhile, the sample with cladding layer cavity also shows a spectral stability as the injected current changing from 20 mA to 100 mA.
Highlights
Because of the substrate absorption and the phenomenon of total internal reflection, AlGaInP LEDs grown on GaAs substrate suffer from a lower extraction efficiency of 2% [1]
Experimental results show that the cladding layer cavity can improve the internal quantum efficiency effectively, so that an external quantum efficiency of 7.4% at 20 mA is reached
The resonant cavity light-emitting diodes (RCLEDs) provide an effective way to improve the external efficiency by enhancing spontaneous emission and directing much light normal to the semiconductor surface [2]
Summary
Because of the substrate absorption and the phenomenon of total internal reflection, AlGaInP LEDs grown on GaAs substrate suffer from a lower extraction efficiency of 2% [1]. Experimental results of the external efficiency for RCLEDs around 650 nm wavelength are still not satisfied [9,10,11,12]. Most efforts such as special mirrors [13], photonic crystal [14] and 2-D grating [15] are made to improve RCLEDs quantum extraction efficiency, while less attention is paid to the internal quantum efficiency which is very important for RCLEDs with a narrow active region. We have designed and fabricated two RCLED samples with different cavity structure at 650 nm wavelength. For the sample with a cladding layer cavity, the internal quantum efficiency nearly reaches 100%, so that an external efficiency nearly reaching the theory limits is obtained
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