Browsing by Subject "Cathodoluminescence"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Open Access Engineered ultraviolet InGaN/AlGaN multiple-quantum-well structures for maximizing cathodoluminescence efficiency(American Institute of Physics Inc., 2022-01-04) Zheng, Haiyang; Sharma, Vijay KumarWe demonstrate a systematic way to understand and select the accelerating voltage for maximizing cathodoluminescence (CL) by correlating the carrier diffusion length with the efficiency of ultraviolet (UV) InGaN/AlGaN multiple quantum wells (MQWs). We showed that the absorption of MQWs benefits from the absorbed energy within the diffusion length below the MQWs. With this understanding, we have achieved good agreement between the experimental data of and the Monte Carlo (CASINO) simulations on the dependence of acceleration voltage and QW number on InGaN/AlGaN MQW structures. These findings indicate that CL-based UV generation from carefully engineered III-N MQW structures with an appropriate number of QWs is highly promising. The understanding and application of this work can be extended to electron-beam pumped devices emitting in deep-UV (200-280 nm) wavelengths. © 2022 Author(s).Item Open Access On-chip mercury-free deep-uv light-emitting sources with ultrahigh germicidal efficiency(Wiley-VCH Verlag GmbH & Co. KGaA, 2021-08-04) Sharma, Vijay Kumar; Tan, S. T.; Haiyang, Z.; Shendre, S.; Baum, A.; Chalvet, F.; Tirén, J.; Demir, Hilmi VolkanIn the current COVID-19 scenario, there is an urgent need for developing efficient and mercury-free deep-ultraviolet (deep-UV) light sources for disinfection applications. AlGaN-based light-emitting diodes (LEDs) may be considered as an alternative, but due to their inherent low efficiencies in the deep-UV spectral region, significant developments are required to address efficiency issues. Here, a mercury-free chip-size deep-UV light source is shown which is enabled by high-vacuum chip-scale cavity sealing overcoming the limitations of both mercury lamps and deep-UV LEDs. These deep-UV chips are cathodoluminescence based, in which a cavity is created with high vacuum integrity for efficient field-emission. These chips demonstrate optical output power ≥20 mW (efficiency ≈4%) and, owing to the spectral overlap of phosphor cathodoluminescence spectra and germicidal effectiveness curve, resulted in log 6 (99.9999%) germicidal efficiency. Additionally, these chips offer high reliability, “instant” ON/OFF capability, high operational lifetimes, and low-temperature dependence with complete design freedom.