Optical Gain in In₀.₃Ga₀.₇N/AlGaN Quantum Dots: Impact of Size, Carrier Density, and Relaxation

This study investigates the optical gain properties of In₀.₃Ga₀.₇N/Al0.2Ga0.8N quantum dots by analyzing both fundamental and higher-order electronic transitions. The results show that the transition energy and optical gain strongly depend on the size of the quantum dots and the energy levels involved. Smaller quantum dots exhibit stronger quantum confinement, leading to higher transition energies and enhanced gain. In addition, the optical gain is shown to increase with carrier density, while the relaxation time significantly affects the spectral broadening and sharpness of the gain peak. Although higher excited states correspond to higher photon energies, their contribution to the optical gain is less significant compared to the fundamental state. These findings provide valuable insights for optimizing the design of quantum dot-based optoelectronic devices, enabling better control of emission wavelength and optical amplification characteristics.