Surface emission enhancement for deep ultraviolet AlGaN-based LEDs using triangular shaped quantum wells

• Modified theoretical model was given to calculating optical polarization properties.
• There is more TE polarized emission component from triangular shaped AlGaN-based QWs.
• Triangular shaped AlGaN-based QWs has shorter polarization switching wavelength.
• Surface emission of DUV AlGaN-based LEDs is enhanced by using triangular shaped QWs.

The optical polarization properties of AlGaN/AlN conventional rectangular shaped and triangular shaped quantum wells (QWs) were investigated using the modified theoretical model based on the effective mass equation. The calculated results show that there is more emission component with TE polarization from triangular shaped QWs than that from conventional QWs for same peak emission wavelength, which is beneficial to the surface emission of Al-rich AlGaN-based light-emitting diodes (LEDs). Furthermore, the AlGaN/AlN triangular shaped QWs have shorter critical wavelength for polarization switching between dominant TE and TM emissions than conventional QWs. This is because that valence subband structure changes for the special band edge potential in AlGaN/AlN triangular shaped QWs. So, the polarization control to enhance the surface emission of DUV AlGaN-based LEDs can be realized by using triangular shaped QWs structure.