A laboratory experiment with blue light-emitting diodes Available to Purchase

We present a laboratory experiment designed to show the main characteristics of blue light-emitting diodes. The analyzed devices are based on III–V nitrides (in which the active layer is a direct band gap In_0.06Ga_0.94N alloy) and SiC (where the active layer is the 6H polytype of this semiconductor, which is of an indirect band gap class). From the measurements, an $In$ relation could be established between light emission and device current, with $n$ values related to both the physical structure and electroluminescence characteristics of these semiconductors. The spectral response measurements allow us to obtain the peak wavelength of emission with reasonable precision (449±4 nm in the former one and 470±4 nm in the last one). It is also possible to accurately obtain the band gap value of the active layer in the device based on III–V nitrides (3.18±0.03 eV) by analyzing its electroluminescence spectra. However, the same analysis is not possible in the SiC-based device due to its extremely low measured luminous intensity values. A comparison of power conversion efficiency of both devices is also given.