Fig. 1. (a) Schematic diagram of the TJ micro-LED. (b) Top view SEM images of TJ micro-LEDs. (c) and (d) TEM images of TJ LED structure and InGaN polarization layer. (e) Experimental and simulated XRD scans along (0002) direction. (f) Depth profiles of Si, Mg, In, and Al concentrations of the TJ LED measured by SIMS.

Fig. 2. (a) Enhanced PL spectra with different device size. (b) Normalized TR-PL spectra of designed TJ micro-LEDs with different device size. Inset shows the relationship between τ1 (τ2) and device size.

Fig. 3. (a) Room temperature J-V characterizations of TJ micro-LEDs and standard micro-LEDs. (b) Temperature dependence of J-V curves for TJ micro-LEDs.

Fig. 4. (a) EL intensity of two samples with device diameter of 40 μm. Inset shows the EL intensity of TJ micro-LEDs with the current density ranging from 2.4×10−5  A/cm2 to 31.85  A/cm2 and the optical micrograph of TJ micro-LEDs measured at 15.92  A/cm2. (b) Dependence of normalized EQE on current density for two kinds of devices.

Fig. 5. (a) J-V characteristics of TJ micro-LEDs with different device size. (b) Relationship between normalized EQE and current density of devices with different device size.