Numerical Simulation Of Optical And Electrical Characteristics In GaN-Based LEDs

The progress of the semiconductor materials contributes to the development of the semiconductor industry. As wide band gap material, Gallium nitride is used for a variety of optoelectronic devices. GaN based light-emitting diode (led) has many advantages compared with the traditional light source, such as multicolor, high efficiency, no pollution. It has vast market prospects. Meanwhile, it remains many aspects needed to be studied to improve the photoelectric characteristics of GaN-based LED. Numerical simulation based on semiconductor theory, such as k-p method, is a fast and reliable way to study the characteristics of GaN-based LEDs, which is helpful to the study of band gap and carrier distribution, especially. In view of the quantum well width and indium composition in the quantum well are both related to the performance of GaN-based LEDs, this thesis investigates two LED devices with different structure in these two aspects, simulating by the APSYS software:(1) Simulating the positive sequence LED structure, with different well width and different In composition. Calculation results indicate that:there is a red-shift in the electroluminescent spectra, and turn-on voltage increasing, light power decreasing, with increasing well thickness(greater than2nm); there is a red-shift in the electroluminescent spectra, and turn-on voltage increasing, light power decreasing, with increasing In composition. Electroluminescence intensity and light power increase with increasing In composition up to a certain value between12%to16%and then decrease with further increasing In composition.(2) Simulating the p-side down LED structure, with different well width and different In composition. Calculation results indicate that:turn-on voltage increasing, carrier distribution separated increasing. Electroluminescence intensity and light power increase with increasing well width up to3nm and then decrease with further increasing well width. But the electroluminescent spectra has a red-shift with increasing well width up to4nm and then has a blue-shift with further increasing well width.P-side down structure has outstanding advantages compared with traditional structure, including a uniform carrier distribution in quantum well, higher internal quantum efficiency and higher light power, although the turn-on voltage is higher.