title: Distinct U-shape efficiency-versus-current curves in AlGaN-based deep-ultraviolet light-emitting diodes.
abstract: The efficiency of an AlGaN deep-ultraviolet light-emitting diode with peak emission wavelength of 285 nm is investigated as a function of current over a wide range of temperatures (110 K to 300 K). We find that the efficiency-versus-current curve exhibits unique and distinct features over the entire temperature range including three points of inflection. At low temperatures, the change in slope in the efficiency-versus-current curve is particularly pronounced producing a minimum in the efficiency after which the efficiency rises again. Furthermore, at high current density, the low-temperature efficiency exceeds the room-temperature efficiency. The feature-rich efficiency-versus-current curve is consistent with an enhancement in p-type conductivity by field-ionization of acceptors that occurs in the high-injection regime and is particularly pronounced at low temperatures. Differential conductivity measurements show a marked rise in the high-injection regime that is well correlated to the minimum point in the efficiency-versus-current curve.
authors.forename: Jun Hyuk
authors.initials: JH
authors.lastname: Park
authors.forename: Guan-Bo
authors.initials: GB
authors.lastname: Lin
authors.forename: Dong Yeong
authors.initials: DY
authors.lastname: Kim
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Lee
authors.forename: Jaehee
authors.initials: J
authors.lastname: Cho
authors.forename: Jungsub
authors.initials: J
authors.lastname: Kim
authors.forename: Jinsub
authors.initials: J
authors.lastname: Lee
authors.forename: Yong-Il
authors.initials: YI
authors.lastname: Kim
authors.forename: Youngsoo
authors.initials: Y
authors.lastname: Park
authors.forename: E Fred
authors.initials: EF
authors.lastname: Schubert
authors.forename: Jong Kyu
authors.initials: JK
authors.lastname: Kim