Effects of electrochemical potentiostatic activation on carrier transport in AlGaN-based deep-ultraviolet light-emitting diodes

Abstract

Electrochemical potentiostatic activation (EPA) is applied to AlGaN-based deep-ultraviolet (DUV) light-emitting diodes (LEDs). The effects of EPA on DUV LEDs are disclosed by analyzing the temperature-dependent current-voltage characteristics. EPA-treated DUV LEDs show improved electrical optical properties with suppressed forward leakage currents, reduced operation voltages, smaller ideality factors, and enhanced light emission compared to the reference device. EPA treatment yields distinct differences in carrier conduction across the p-AlGaN layer. The limited conductivity of the p-AlGaN layer in a DUV LED causes space-charge-limited (SCL)-like conduction behavior in the voltage regime far exceeding the turn-on voltage. EPA treatment alleviates the SCL-like conduction, which infers the improved conductivity of the p-AlGaN layer. In the same vein, the occurrence of high-level injection is retarded in the EPA-treated device, which is also consistent with enhanced conductivity of the p-AlGaN layer that mitigates asymmetry between n- and p-type conductivities of a DUV LED. Thus, the improved performance of AlGaN-based DUV LED is attributed to the promoted charge transport, which is enabled by the EPA-induced enhanced p-type conductivity.