Exploiting the Negative Polarization Properties of Indium Gallium Nitride (InGaN)/Gallium Nitride (GaN) Heterostructures to Achieve Frequency Doubled Blue-green Lasers with Deep UV (<250 nm) Emission (Year 2)

There is an Army need to develop deep ultraviolet UV semiconductor lasers that are compact with a low power budget for use in real-time reagentless biodetection and identification systems as well as water monitoring. Our approach is to develop a visible indium gallium nitride InGaN-based laser that exploits the negative polarization charge at the heterointerface, which can then be frequency doubled into the deep UV. In the second year of this Director s Research Initiative DRI, we focused on the growth and development of periodically poled AlGaN to be used for frequency doubling the visible laser light into the deep UV DUV. To accomplish this, we have demonstrated the successful growth of inverted, N-polar AlN, which was achieved by Mg overdoping using a larger inversion layer thickness than for N-polar GaN. We have demonstrated a sub-micron periodic poled AlN by e-beam lithography, ICP etching, and MBE regrowth.