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| Home > Publications database > Tuning III-nitride nano-LEDs via laser-micro-annealing |
| Conference Presentation (After Call) | FZJ-2023-00998 |
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2022
Abstract: Conventional reactive ion etching (RIE) used for the space definition/formation of nano-LEDs leads to a significant decrease in their electroluminescence. Among all the technological approaches to boost the efficiency of micrometer and nano- sized LED structures, the precise local laser micro annealing (LMA) procedure exhibits still undiscovered potential. The main goal behind the application of the “LMA” procedure is to “adjust” and/or to “engineer” the emission intensity of nano-LEDs according to requirements for example in transmistor based optical computing architectures currently under development. Here in this work, we present correlative ̶ optical (micro electro- & photoluminescence, Raman spectroscopy) and electrical ̶ characterization of single nano-LEDs in arrays integrated into a vertical device layout. Scanning electron microscopy investigations (figure 1) reveal inhomogeneous surface nano-LED morphology. Micro photoluminescence studies indicate that the LMA process has a direct impact on the curing of etching related defects. These are responsible for the suppression of radiative recombination in the nano-LED devices. Figure 2 presents a micro electroluminescence mapping after the successful “conditioning” procedure performed on nano-LEDs in an array with different annealing conditions. Furthermore, micro-Raman thermography investigations performed on single nano-LED structures (after LMA) disclose an up to 60K decrease in work temperature. Additionally, long-term operation electroluminescence measurements (up to 5000 hours) indicate that the LMA approach affects the nano-LEDs performance as well as device lifetime and reliability advantageously. The results presented demonstrate the suitability and reliability of the vertically integrated nano-LEDs conditioned locally/selectively by LMA as a key component for future on chip integrated electro-optic convertors. They could play an important role in the development of novel optical computing architectures based on transmistor/all optical switch units. Figure 1: Scanning electron micrograph of a single nano-LED structure with its nickel cap (serving as the etching mask) after the RIE process. The “base” region of the nano-LED exhibits a “shallower” chemical/physical corrosion depth. Figure 2: micro electroluminescence map-ping, after the “conditioning” procedure, performed on nano-LEDs in an array with different annealing conditions: non-locally annealed E0 and locally E1 and E2 annealed.
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