Observation of space-charge-limited current in AlGaN/GaN ultraviolet light-emitting diodes

Abstract

AlGaN-containing ultraviolet light-emitting diodes (UV LEDs) emitting at 285 nm show abnormal diode characteristics below the sub-threshold input voltage region, indicating the existence of a space-charge-limited (SCL) current. Distinct transitions from Ohmic to SCL and further diode currents are observed in UV LEDs, unlike GaInN-based LEDs. Under varied temperatures, the transition voltages from Ohmic to SCL currents and the exponents of the power functions in the current-voltage dependency are influenced by the deactivated trap density in the AlGaN film, indicating that the charge injection and compensation limit for the current within the films in the low-voltage regimes for nitride-based UV LEDs. (C) 2017 Elsevier B.V. All rights reserved.