  Ultra-violet emitters have several applications in the areas of sensing,
water purification, and data storage. While the III-Nitride semiconductor
system has the band gap region necessary for ultraviolet emission, achieving
efficient ultraviolet solid state emitters remains a challenge due to the low
p-type conductivity and high contact resistance in wide band gap AlGaN-based
ultra-violet light emitters. In this work, we show that efficient interband
tunneling can be used for non-equilibrium injection of holes into ultraviolet
emitters. Polarization-engineered tunnel junctions were used to enhance
tunneling probability by several orders of magnitude over a PN homojunction,
leading to highly efficient tunnel injection of holes to ultraviolet light
emitters. This demonstration of efficient interband tunneling introduces a new
paradigm for design of ultra-violet light emitting diodes and diode lasers, and
enables higher efficiency and lower cost ultra-violet emitters.
