The influence of the coating metals with various work function on the photoluminescence of a GaN-based blue LED wafer

A GaN light emitting diodes (LED) wafer was coated with Pt, Au, Al and In. The photoluminescence (PL) excited from wafer back shows that Pt and Au coating can quench the PL while In and Al can increase the PL intensity by eight times and make the wavelength red shift. When connected to the Pt with a wire, indium can also quench the PL. The potential difference between any two kinds of the metals was measured and the PL intensity from each coated area showed a remarkable pertinence to the coating metal potentials. A built-in potential barrier model is proposed to explain results.