A subversive innovation on GaN P-type reflective electrode using electroless silver plating

In this work, we first proposed an innovation on GaN p-type reflective electrode in flip-chip LEDs (FCLEDs) using a novel method so called electroless silver plating (ESP). In our ESP method, we use chemical way to form a perfect Ag reflector, differ from traditional fabrication of p-type reflective electrode using electron beam deposition (EB). Under our investigation, the Ag reflective electrode formed by ESP possesses better optical and electric characteristics. Compared with EB, the reflectance of electrode by ESP over the whole visible light spectrum was 93%, higher than EB samples, which only show 82%. Otherwise, ohmic contact characteristic between metal and GaN also shows the same rule as reflectance. ESP samples exhibit better specific contact resistance than EB samples, they´re 6.5 * 10^-3Ω · cm² and 6 * 10^-2Ω· cm², respectively. Moreover, the fantastic results of I-V as well as L-I measurement likewise verify electroless silver plating to be a potential manufacturing technology of p-type reflective electrode.