AlGaN Light-Emitting Diodes on AlN Substrates Emitting at 230nm

Light-emitting diodes with emission wavelengths between 230 and 240nm are grown on AlN substrates and characterized optically and electrically. Optimized doping of the n-AlGaN with Si has resulted in a mean forward voltage at 200mA of 9V. The electroluminescence spectra is demonstrated to be free of long wavelength parasitic emission. An envelope function in the output power versus peak wavelength is shown, demonstrating the increasing dominance of in-plane emission at shorter wavelengths as light extraction becomes more difficult. However, variations in device structure show that further optimization of the structure for carrier confinement and injection efficiency are also able to push performance beyond the current state of the art.