Lateral Optimization Design Of Electron Blocking Layer For AlGaN-based Deep Ultraviolet Light Emitting Diode

AlGaN-based Deep Ultraviolet Light Emitting Diode(DUV-LED)is a noval solid-state light source.At present,many researchers only focus on the vertical optimization of the LED structure rather than paying more attention to the lateral improvement.This paper proposes the lateral optimization of the stepped and graded electron blocking layer(EBL),supplemented by p-doped quantum barriers,to improve the luminous performance of DUV-LED.The main contents are as follows.(1)Introduce the lateral stepped EBL in DUV-LED to study the influence on the device performance.It is found that the lateral optimization can effectively suppress the leakage of electrons and improve the hole injection in the active area.The light output power(LOP)of the device with the reducing stepped Al composition of EBL can be maximum increased by 16.7%compared to the traditional structure.What is more,the internal quantum efficiency(IQE)and the efficiency droop at the high injection current are also ameliorated.(2)Introduce a structure that combines p-doped quantum barriers with the laterally stepped EBL.When the five quantum barriers close to the p-EBL are all p-doped,the LOP and IQE are all significantly improved.The doping concentration also has a great influence on the luminous performance.Especially when the concentration reaches5×10¹⁸cm^-3,the device gets the optimal luminous performance with the greatly increased hole concentration and improved polarization electric field inside the active region.(3)Laterally graded EBL of the DUV-LED is proposed based on the stepped EBL.Compared with the laterally stepped EBL,the graded one can reduce the conduction effective barrier height of the quantum barriers and increase the electron concentration in the active region.The polarization effect inside the quantum wells is improved greater.Compared with the traditional structure and the laterally stepped EBL structure,the LOP of the DUV-LED with graded EBL has increased by 74.7%and 50.6%,respectively.The IQE is also greatly increased that the maximum IQE reaches 51.8%,and the efficiency droop can be reduced to 22%.The lateral optimization of the AlGaN-based DUV-LED effectively ameliorates the carrier concentration and polarization effect,significantly improves the light output power and internal quantum efficiency.This paper provides a new idea for the optimization design of DUV-LED.