Large Optical Gain AlInN-Delta-GaN Quantum Well for Deep Ultraviolet Emitters.

Chee-Keong Tan,Nelson Tansu,Damir Borovac,Wei Sun

doi:10.1038/srep22983

Abstract

The optical gain and spontaneous emission characteristics of low In-content AlInN-delta-GaN quantum wells (QWs) are analyzed for deep ultraviolet (UV) light emitting diodes (LEDs) and lasers. Our analysis shows a large increase in the dominant transverse electric (TE) polarized spontaneous emission rate and optical gain. The remarkable enhancements in TE-polarized optical gain and spontaneous emission characteristics are attributed to the dominant conduction (C)-heavy hole (HH) transitions achieved by the AlInN-delta-GaN QW structure, which could lead to its potential application as the active region material for high performance deep UV emitters. In addition, our findings show that further optimizations of the delta-GaN layer in the active region are required to realize the high performance AlInN-based LEDs and lasers with the desired emission wavelength. This work illuminates the high potential of the low In-content AlInN-delta-GaN QW structure to achieve large dominant TE-polarized spontaneous emission rates and optical gains for high performance AlN-based UV devices.

Highlights

In comparison to the advances in the InGaN-based light emitting diodes (LEDs) in the blue and green emitting regime[32,33,34,35,36,37,38,39,40,41,42,43,44], the AlGaN-based quantum wells (QWs) DUV-LEDs still suffer from the low external quantum efficiency (EQE) issue[8,9,10,11]
QW with low In-content to achieve sufficient spontaneous emission rates for high performance UV LEDs. This is attributed to the fact that the conventional AlInN QWs with In-content of 8% suffers from the valence band crossover issue, which leads to a small value of transverse electric (TE)-polarized optical gain
Our analysis demonstrates the importance of applying the delta-GaN layer in the conventional AlInN QW, in order to enhance the dominant TE-polarized optical gain for high performance deep UV lasers

Summary

GaN Quantum Well for Deep

The optical gain and spontaneous emission characteristics of low In-content AlInN-delta-GaN quantum wells (QWs) are analyzed for deep ultraviolet (UV) light emitting diodes (LEDs) and lasers. The remarkable enhancements in TE-polarized optical gain and spontaneous emission characteristics are attributed to the dominant conduction (C)-heavy hole (HH) transitions achieved by the AlInN-delta-GaN QW structure, which could lead to its potential application as the active region material for high performance deep UV emitters. This work illuminates the high potential of the low In-content AlInN-delta-GaN QW structure to achieve large dominant TE-polarized spontaneous emission rates and optical gains for high performance AlN-based UV devices. A different approach has been suggested by employing AlGaN-delta-GaN QW structure, in which the valence bands are rearranged, leading to dominant TE-polarized emission[23,24] These approaches focused in the use of AlGaN alloy in the active region, while the approach on using different III-Nitride UV materials is relatively unexplored. Note that in the conventional AlInN QW, due to the built-in polarization field the electron and hole wavefunctions being spatially separated, a lower electron-hole wavefunction overlap is observed

Results and Discussion

Conclusion

Additional Information