Thermal resistanse and nonuniform distribution of electroluminescence and temperature in high-power AlGaInN light-emitting diodes

The paper studies current spreading, light emission, and heat transfer in high-power flip-chip light-emitting diodes (LEDs) and their effect on the chip thermal resistance by experimental and theoretical approaches. The thermal resistance was measured using two methods: by monitoring the transient response of the LED operation voltage to the temperature variation with the Transient Tester T3Ster and by temperature mapping with the use of an infrared thermal-imaging microscope. The near field of the electroluminescence intensity was recorded with an optical microscope and a CCD camera. Three-dimensional numerical simulation of the current spreading and heat transfer in the LED chip was carried out using the SimuLED package in order to interpret the obtained experimental results

Deep green and monolithic white LEDs based on combination of short-period InGaN/GaN superlattice and InGaN QWs

International audienceThis work presents the results of the investigation of approaches to the synthesis of the active region of LED with extended optical range. Combination of short‐period InGaN/GaN superlattice and InGaN quantum well was applied to extend optical range of emission up to 560 nm. Monolithic white LED structures containing two blue and one green QWs separated by the short‐period InGaN/GaN superlattice were grown with external quantum efficiency up to 5–6%

Monolithic white LEDs: Approaches, technology, design

International audienceThe results of investigations of monolithic white InGaAlN LEDs with an active region containing several thin InGaN layers, emitting in the range from blue to yellow-green, and separated by short-period InGaN/GaN superlattices, are presented. The influence of the growth conditions and layer sequence in the active region on the optical properties of monolithic white LEDs was studied with the aim of controlling their color parameters