Real-time near-field evidence of optical blinking in the photoluminescence of InGaN by scanning near-field optical microscope

InGaN/GaN devices are currently used for many applications, for example, full color display, white (RGB) illumination systems and for the realization of shorter wavelength emitters for optical data storage. We previously reported a blinking phenomenon in the photo-luminescence of InGaN device ready single quantum well materials. In this study we observe in high resolution this optical instability with a near-field nano-probe. The phenomenon appears only in local confined domains and does not seem to behave as a bistable state process like reported on quantum dots generated photo-luminescence. We investigated by a modified scanning near-field optical microscope (SNOM) and studied the time/intensity profile of the optical signal with a resolution in the range of 100nm. The dynamics of the blinking was time-resolved and its behaviour studied with Fourier analysis. Despite the intensity oscillations were found to have chaotic component (autocorrelation coefficient is about 0.63), the optical oscillations appear to include regular characteristics. Fourier analysis of the light intensity from confined domains exhibit peaks in the range of 4-5 s. The emergence of these intriguingly slow and partially regular dynamics should shed light on the inner mechanism that are involved in the fundamental processes of optical emission in these devices. (C) 2011 Optical Society of America