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▲ [15p-B401-4] Improvement of InGaN-based LEDs efficiency by current-blocking region realized via hydrogen passivation
Keywords:InGaN LED, Hydrogen Passivation
Here, we report further exploration of selective passivation of p-GaN by hydrogen plasma, following previous works of our group[1, 2]. Exposure to the hydrogen plasma deactivates the Mg dopants in the p-GaN, increasing its resistance up to 10 times[1]. Using that, we have created the Current Blocking Regions (CBRs) on the LED p-side. Therefore, the CBRs are situated between p-GaN and Indium Tin Oxide layers.
We have fabricated the standard-size (280x800 μm2) green InGaN LED chips in three variants, the reference device along with two variations of the CBR pattern. In the first case, CBR is introduced underneath the opaque metal p-pad of the device. In the second case, along with the p-pad area, CBR additionally encircles the perimeter of the device mesa. Thus, the current injection into the sidewall region is suppressed, reducing the probability of the non-radiative recombination on the dry-etching induced defects. The resulting dark frame is clearly visible in Figure 1 (b). The application of the CBR technique has resulted in up to 1.23 times increase of the device’s peak on-wafer EQE and shift of the peak EQE position towards lower injection current densities[3], as it is shown in Figure 2.
We have fabricated the standard-size (280x800 μm2) green InGaN LED chips in three variants, the reference device along with two variations of the CBR pattern. In the first case, CBR is introduced underneath the opaque metal p-pad of the device. In the second case, along with the p-pad area, CBR additionally encircles the perimeter of the device mesa. Thus, the current injection into the sidewall region is suppressed, reducing the probability of the non-radiative recombination on the dry-etching induced defects. The resulting dark frame is clearly visible in Figure 1 (b). The application of the CBR technique has resulted in up to 1.23 times increase of the device’s peak on-wafer EQE and shift of the peak EQE position towards lower injection current densities[3], as it is shown in Figure 2.