A 310 nm Optically Pumped AlGaN Vertical-Cavity Surface-Emitting Laser.

Filip Hjort,Arne Knauer,Åsa Haglund,Tim Wernicke,Johannes Enslin,Ines Häusler,Markus R Wagner,Johan Gustavsson,Felix Nippert,Munise Cobet,Michael A Bergmann,Tim Kolbe,Michael Kneissl

doi:10.1021/acsphotonics.0c01382

Abstract

Ultraviolet light is essential for disinfection, fluorescence excitation, curing, and medical treatment. An ultraviolet light source with the small footprint and excellent optical characteristics of vertical-cavity surface-emitting lasers (VCSELs) may enable new applications in all these areas. Until now, there have only been a few demonstrations of ultraviolet-emitting VCSELs, mainly optically pumped, and all with low Al-content AlGaN cavities and emission near the bandgap of GaN (360 nm). Here, we demonstrate an optically pumped VCSEL emitting in the UVB spectrum (280–320 nm) at room temperature, having an Al0.60Ga0.40N cavity between two dielectric distributed Bragg reflectors. The double dielectric distributed Bragg reflector design was realized by substrate removal using electrochemical etching. Our method is further extendable to even shorter wavelengths, which would establish a technology that enables VCSEL emission from UVA (320–400 nm) to UVC (<280 nm).

Highlights

Ultraviolet light is essential for disinfection, fluorescence excitation, curing, and medical treatment
UV light is used for water and surface disinfection, fluorescence excitation, curing, and medical treatment,[14] and the realization of UV vertical-cavity surfaceemitting lasers (VCSELs) could, for example, enable energy-efficient, highthroughput, and compact water purification systems based upon 2D-laser arrays
Previously reported UV VCSELs were mainly optically pumped and all emitted in the UVA (320− 400 nm).[15−21] The low Al-content AlGaN cavities employed in the previous demonstrations are limited to emission wavelengths near the bandgap of GaN (360 nm) and prevent extension into the UVB (280−320 nm) and UVC (

Summary

■ METHODS

10.4 nm HfO2 layer was sputtered before the final DBR to partly compensate for the epitaxially grown AlGaN device layers being thinner than targeted. Details on DBR reflectivity, threshold carrier density, VCSEL design and resonance wavelength, strain state, structural analysis, process flow, and photoluminescence measurements (PDF).

Author Contributions

■ ACKNOWLEDGMENTS

Findings

■ REFERENCES