Midinfrared emission from InGaN/GaN-based light-emitting diodes

Midinfrared emission on violet, blue, and green InGaN light-emitting diodes has been measured between 85 and 300 K for various injection current densities. We found that the diode with the highest In composition in the active region had the shortest midinfrared emission wavelength and vice versa. With increasing In content, a significantly decreasing amount of TM polarization was observed in the midinfrared emission spectrum. This result suggests that the density of states in the higher-In content devices corresponds to a zero-dimensional electronic system rather than a two-dimensional electron gas. In contrast to this, the violet light-emitting diode exhibited a higher degree of TM polarization; similar to a red InGaP-based quantum-well device.