Determining the Turn-On Voltage of GaN-Based Light-Emitting Diodes: From Near-Ultraviolet to Green Spectra

This work investigates the turn-on voltage ( V on ) estimation methods from experimental data of InGaN-based multiple-quantum-well light-emitting diodes (LEDs) with emission spectra from near-ultraviolet to green wavelengths. Three different methods are examined: fixed current intercept, linear fitting of current-voltage curve, and the minimum ideality factor ( n ideal ). The voltage at minimum n ideal consistently represents the on-state of LEDs since it describes the carrier recombination processes reflected in light output power (LOP) and the external quantum efficiency (EQE). Beyond the voltage at minimum n ideal , samples’ LOPs start to increase abruptly, with the EQEs reaching ≥ 54% of the peak EQE values. For V on determined by other methods, samples’LOPs are already turned on and the EQEs exceed their peak value. Therefore, using the minimum n ideal is a suitable method for determining V on of an LED.