Enhanced performance of flexible LED by low-temperature annealing

The ohmic contact of n-GaAs having surface treatment was achieved at 300 degrees C. It shows that surface treatment makes the GaAs easier to form an ohmic contact with Ni/Au/Ge/Ni/Au multilayer. Low-temperature annealing was applied to flexible AlGaInP/GaInP multi-quantum well red LED @630 nm wavelength, whose substrate is replaced by an electroplated Cu thin film from the thick GaAs substrate. The measured current-voltage properties exhibit a much-reduced turn-on voltage, which decreased from 3.75 to 1.5 V. The light output power current measurement shows that the output power reduction, only 2%, in flexible LEDs is insignificant. This work provides a way to improve the performance of flexible optoelectronic devices.