Research Of InGaN/GaN MQWs Growth With Different Showerhead Gap Position And Simulation Of The Advantages In N-AlGaN EBL

Light-emitting diodes (LEDs) had demonstrated huge application potential since it was invented. Especially for the advent of nitride materials, emitting efficiently blue or green light, expanded enormously the LED application scope. Nowadays, LED has generally used in many applications, such as LED full-color display, traffic lights, and white lighting sources, which can be the new generation of environmentally solid-state lighting sources. Thus, many researchers have started to investigate the methods of improving their performance. For GaN based LED, there are two common ways to improve the performance, one is to improve the quality of each layer by changing growth conditions, the other is to optimize LED structure.Considering the two subjects above, the paper contains two works:the research of InGaN/GaN MQWs growth with different showerhead gap position, and the inflence of EBL on the LED performance. Details are as follows:(1) A series of InGaN/GaN MQWs samples were grown with four different showerhead gap position,7,13,18,25mm, using Axitron CCS-MOCVD system. Through the measurement results, we find that the surface morphology, interface quality, thickness of QB and QW, In composition and PL spectrum of samples are all change significantly. This can attributes to the change of temperature field, flow field and concentration field in the reactor due to the different showerhead gap position. Moreover, the showerhead gap position also affects the pre-reaction in the reactor, which result in converting the thickness of QB, QW and In composition. Consequently, it makes the PL spectrum different.(2) Two LED samples with n-AlGaN EBL and without EBL were simulated using Apsys simulation software. The advantages of n-AlGaN EBL were studied through the energy band diagram, carrier distribution diagram, electroluminescence EL, current-power diagram, internal quantum efficiency IQE and current-voltage I-V diagram we obtained. From the result, we realize that the insertion of n-Alo.o5Gao.95N EBL makes the carrier concentration and distribution changed and improve the optical and electrical performance of LED. This phenomenon is mainly due to the good confine of electron within the MQWs and enhancement of hole concentration.