Design of AlGaN-based lasers with a buried tunnel junction for sub-300 nm emission

Abstract

This paper discusses the design of electrically-pumped AlGaN-based in-plane lasers emitting at ∼290 nm. Our laser design utilizes strained Al 0.5 Ga 0.5 N quantum wells, and a novel polarization engineered AlGaN/InGaN/AlGaN-based tunnel junction. The low resistive tunnel junction is used as an intracavity contact in the device in place of the resistive p-type contact; which leads to improved hole injection and a reduced threshold voltage. Hence, room-temperature continuouswave laser operation could be enabled. Strategies to improve the performance of the tunnel junction contact through the incorporation of low concentrations of boron in the highly-doped AlGaN tunnel junction layers as a means to increase the polarization sheet charge are also discussed.

Low voltage drop AlGaN UV-A laser structures with transparent tunnel junctions and optimized quantum wells

“…The 2D spatial mode distribution of fundamental TE mode is shown in figure 3(b). Although previously it was suggested that an asymmetric waveguide [14][15][16] is optimum for reducing optical absorption loss in a laser structure with a heterojunction TJ having an absorbing interlayer, in this design, we opted for a symmetric waveguide structure. This choice was made because our homojunction TJ is transparent and will not absorb the light generated by the active region.…”

“…To overcome all these drawbacks, laser structures with compositionally graded transparent tunnel junctions (TJs) along with an optimized QW active region show promise. The implementation of such TJs in a laser structure allows for the replacement of the resistive p-type contact and p-AlGaN cladding layer with n-AlGaN cladding layers on both the pand n-side of the laser structure [14,15]. As n-AlGaN cladding layers have lower activation energy for dopants compared to p-AlGaN layer and can form low-resistance ohmic contacts with better current spreading, this laser structure provides improved electrical properties while maintaining low optical losses [16].…”

Towards Efficient Electrically-Driven Deep UVC Lasing: Challenges and Opportunities

“…Note that lasers can be operated under optical, electrical (electrically-driven), or electron beam (electron gun) excitation. All these three approaches have been already utilized to demonstrate III-nitride-based DUV lasers [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. Undoubtedly, electrically-driven laser diodes (LDs) that can deliver high optical output powers at specified wavelengths and, at the same time, are robust, reliable, and portable, are more desirable due to their durability and compactness when compared to optically- or electron-beam-pumped counterparts.…”