High-performance, single-pyramid micro light-emitting diode with leakage current confinement layer

Abstract

A high-performance, electrically driven, single-pyramid, micro light-emitting diode (micro-LED) was demonstrated. An insulated SiO2 layer, which served as a leakage current confinement layer (LCC layer), was deposited at the lower part of the pyramid, before the deposition of the transparent conducting layer. The micro-LED with the LCC layer demonstrated a decrease in reverse leakage current by two orders of magnitude and a 190% increase in light output at 500 µA compared to a micro-LED without an LCC layer. The small leakage current enables the micro-LED to operate with an ultra-low injection current (<1 µA). The improved performance of the micro-LED is attributed to the presence of the LCC layer, which blocks the direct pathway of the leakage current via threading dislocations distributed at the lower part of pyramid and causes carriers to be injected more effectively into the active layers at the nearly defect-free apex of the pyramidal LED.

Improvement of the Emission Intensity of GaN-Based Micro-Light Emitting Diodes by a Suspended Structure

“…The bias voltage under 20 mA is 5.7 V, and the reverse leakage current under a bias voltage of −5 V is ∼90 nA, which are among the typical values for GaN-based micro-LEDs. 37,38 Figure 6b shows the current-dependent EL spectra of the suspended device. With the injection current increasing from 1 to 20 mA, the central wavelength of the EL spectra shows a slight blueshift from 456.7 to 452 nm, and the FWHM increases from 20 nm to 32 nm because of the band-filling effect.…”

Recent Progress in Micro‐LED‐Based Display Technologies

“…have reported pyramidal micro‐LED, in which reverse current leakage was minimized by a factor of two by employing SiO 2 current confinement layer as shown in Figure 1a. [ 65 ] Consequently, the light output power was enhanced approximately more than twice (Figure 1b). Wong et al.…”

“…Reproduced with permission. [ 65 ] Copyright 2015, The Japan Society of Applied Physics. c) Schematic diagram of µ‐LED with sidewall passivation layer by using ALD.…”

Recent Advances on GaN-Based Micro-LEDs

“…The device structure is shown in Figure 4, they found that SiO2 passivation was more effective than Al2O3 and Si3N4 passivation was more effective in reducing sidewall defects, and µLEDs with SiO2 passivation exhibited high PL efficiency, high optical output power and high current density due to the fact that the Ga-O bond formation energy was lower than the Si-O bond dissociation energy, and at the interface between the GaN and the passivation layer, a great deal Ga-O bonds were formed. According to the results of experiments, the electrical and optical characteristics of the devices can be somewhat improved by the passivation layers grown by the PECVD systems, for example, by improving light extraction efficiency and reducing leakage currents [57,58]. However, because PECVD methods are unable to produce passivation layers with extremely compact atom arrays, some surface defects may not be effectively passivated [59].…”