Full InGaN red light emitting diodes

The full InGaN structure is used to achieve red light emitting diodes (LEDs). This LED structure is composed of a partly relaxed InGaN pseudo-substrate fabricated by Soitec, namely, InGaNOS, a n-doped buffer layer formed by a set of InxGa1-xN/GaN superlattices, thin InyGa1-yN/InxGa1-xN multiple quantum wells, and a p doped InxGa1-xN area. p-doped InGaN layers are first studied to determine the optimal Mg concentration. In the case of an In content of 2%, an acceptor concentration of 1x10(19)/cm(3) was measured for a Mg concentration of 2x10(19)/cm(3). Red electroluminescence was then demonstrated for two generations of LEDs, including chip sizes of 300x300 mu m(2) and 50x50 mu m(2). The differences between these two LED generations are detailed. For both devices, red emission with a peak wavelength at 620nm was observed for a pumping current density of 12A/cm(2). Red light-emission is maintained over the entire tested current range. From the first to the second LED generation, the maximum external quantum efficiency, obtained in the range of 17-40A/cm(2), was increased by almost one order of magnitude (a factor of 9), thanks to the different optimizations.