Abstract
A systematic study was carried out for strain-induced microscale compositional pulling effect on the structural and optical properties of high Al content AlGaN multiple quantum wells (MQWs). Investigations reveal that a large tensile strain is introduced during the epitaxial growth of AlGaN MQWs, due to the grain boundary formation, coalescence and growth. The presence of this tensile strain results in the microscale inhomogeneous compositional pulling and Ga segregation, which is further confirmed by the lower formation enthalpy of Ga atom than Al atom on AlGaN slab using first principle simulations. The strain-induced microscale compositional pulling leads to an asymmetrical feature of emission spectra and local variation in emission energy of AlGaN MQWs. Because of a stronger three-dimensional carrier localization, the area of Ga segregation shows a higher emission efficiency compared with the intrinsic area of MQWs, which is benefit for fabricating efficient AlGaN-based deep-ultraviolet light-emitting diode.
Highlights
AlGaN-based deep-ultraviolet (DUV) light-emittingdiodes (LEDs) have various applications including sterilization and disinfection, water and air purification, medical diagnostics, high density optical recording, information sensing, bio-chemistry, and security [1,2,3]
At present, the efficiency and power of AlGaN-based DUV Light-emitting diode (LED) are still relatively low compared with their visible counterparts that constructed by InGaN and GaN
Most of the reported external quantum efficiency (EQE) of AlGaN-based DUV LEDs is below 20% [11, 12]
Summary
AlGaN-based deep-ultraviolet (DUV) light-emittingdiodes (LEDs) have various applications including sterilization and disinfection, water and air purification, medical diagnostics, high density optical recording, information sensing, bio-chemistry, and security [1,2,3]. We conduct systematic study for the strain-induced microscale compositional pulling effect on the structural and optical properties of high Al content AlGaN MQWs combining characterization and simulation.
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