Enhanced light output of InGaN LEDs with a roughened p-GaN surface using different TMGa flow rates in p-AlGaN layer

Abstract: We have demonstrated the enhancement of light output of InGaN-based blue light-emitting diodes (LEDs) using different trimethylgallium (TMGa) flow rates in the growth of p-AlGaN epilayer to facilitate a rougher p-GaN surface. It is found that higher output power can be achieved from the LEDs with rougher surface morphologies when the TMGa flow rate (R TMGa) is increased up to 60sccm during p-Al0.05Ga0.95N epilayer growth. Such a rough surface obtained at higher R TMGa is attributed to the fact that the vertical growth rate is faster than the lateral growth rate, thus, leading to the facet of crystal growth focuses mainly in the vertical direction. The output power of devices biased at 20mA is 15.4, 15.9, 17.5, and 18.9mW for TMGa flow rates of 10, 20, 40, and 60sccm, respectively. [Copyright &y& Elsevier]