覆晶式發光二極體P型氮化鎵高反射鉑/銀/鉑/金歐姆電極之研究

Abstract

我們利用鉑/銀/鉑/金的金屬組合，具有高反射率及低電阻的特性，運用在p型氮化鎵歐姆接觸電極上，經過270℃熱處理之後，鉑與p型氮化鎵半導體相互擴散形成鉑-鎵合金，半導體中鎵金屬的空缺增加p型氮化鎵載子濃度，降低蕭基接面位障，使費米能階往低能量方向移動，在外加偏壓時形成良好的歐姆接觸。在電流20mA下的順向電壓值可降低至2.96V，在波長470nm的反射率也可維持在高水準86%，運用在覆晶式元件軸向光強度比傳統覆晶發光二極體元件提升36%。

Pt/Ag/Pt/Au multiple layer structure was used as highly reflective and low-resistivity Ohmic contact to the p-type semiconductor. Under 270oC heat treatment, inter-diffusions between Pt and Ga atoms at the interface of the metal contact and the p-ype GaN occur. It results an increase in the carrier concentration in the p-type GaN and further lowers the Schottky barrier and Fermi level to form good Ohmic contact. At 20 mA injection, the turn-on voltage can be reduced to 2.96 V and the reflectivity can be maintained at 86% at 470 nm. The luminous intensity of flip-chip LED with mirror system is raised by 36% higher than that of conventional flip-chip LED.