Improvement of green LED by growing p-GaN on In_0.25GaN/GaN MQWs at low temperature

The effect of temperature on the growth of p-GaN on In_0.25GaN/ GaN multiple quantum well (MQW) in a green light-emitting diode (LED) was investigated. p-GaN was grown at a low temperature of 900 °C to prevent the thermal degradation of MQWs in the green LED. A green LED with low-temperature (LT) p-GaN did not show a blue-shift in its electroluminescence (EL) spectrum, which is frequently observed in InGaN/GaN MQW with a high indium content. X-ray diffraction, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy analyses of the MQW showed that the improved structural quality of MQWs with a LT p-GaN can be attributed to the suppression of inter-diffusion and the re-evaporation of indium in the MQW layers. Current-voltage measurement of the pure green LEDs with a LT p-GaN showed a forward voltage of 3.6 V at 20 mA and the peak wavelength and full-width at half-maximum for the EL emission peak were 525 and 25 nm, respectively.