Optical micrograph of the fabricated LEDs with dimensions ranging from 10 to .
(a) Size-dependent I-V characteristics, (b) J-V plots, and (c) extracted series resistance from I-V curves plotted in (a). The solid line and dashed line are the corresponding fitting curves by using Eqs. (1) and (2).
(a) Output power as a function of injection current for the different pixel sizes. (b) Power density against current density for different pixel sizes. Inset of (b) shows the power densities in the low current density region. For better illustration of the size-dependent extraction efficiency, only the data of three representative pixels are shown in the inset.
(a) Current-density-dependent EL characteristics for the . (b) Current-density-dependent EL characteristics for the . (c) EL shift as a function of current density for different pixel sizes. The dotted lines in (a) and (b) are guides to the eyes showing the shift in peak EL wavelength, as determined by fitting Gaussian functions to the experimental spectra to eliminate interference features.
Measured junction temperature as a function of the current density for different pixel sizes.
Simulated junction-temperature distribution in the active area of (a) the and (b) under the same current density of [picture sizes are not scaled; in the simulation, the n-contact is fixed at the left side, as indicated by the dashed rectangles in (a) and (b)]. (c) Simulated average junction temperature against current density for two different pixels. Note that in (a) and (b) the absolute temperature variation across the device is 28 times larger for the larger device.
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