The optical performance of red-light emitters grown along polar orientation InGaN/(In)GaN multiple quantum well (MQW) with semi-polar structure are examined and compared.
Given a colour of the emitted light, time-resolved photoluminescence (TRPL) measurements show a large difference of decay times between polar and semi-polar structures, when temperature varies in 8 K to 300 K range. The TRPL results evidence a weak internal electric field for the semi-polar structure as the decay time in this structure is slightly wavelength-dependent and is, at a given wavelength, two orders of magnitude smaller than for the polar sample.
The Auger non-radiative recombination is probed by the evolution of the PL intensity with changing photo-excitation power density. In the semi-polar structure, the Auger non-radiative recombination is observed at a threshold PT of photo-excitation density 200 times smaller than in the polar oriented sample. This observation is linked to the difference in efficiency of the localization effect ( different indium compositions) and impact of the quantum confined Stark effect (QCSE) for polar and semi-polar samples. Both localization effect and the QCSE facilitate the establishment of carrier-carrier repulsions before the radiative recombination of electrons and holes occurs. This favor Auger non-radiative recombination process and hence leads to the decrease of the IQE. The smaller threshold PT of the semi-polar oriented structure indicates that the QCSE dominates the reduction of the IQE at high injection level rather than the localization. The semi-polar oriented structure is one promising structure for growth red-light emitters with strong luminescence.
Thi Huong Ngo, Bernard Gil , Benjamin Damilano , Aimeric Courville, and Philippe De Mierry, "Polar and semi-polar oriented InGaN-(In)GaN multiple quantum wells for red-light emitters (Conference Presentation)," Proc. SPIE 10532, Gallium Nitride Materials and Devices XIII, 105321Z (Presented at SPIE OPTO: February 01, 2018; Published: 14 March 2018); https://doi.org/10.1117/12.2287399.5751531016001.
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