應用於覆晶式紫外光發光二極體之低電阻、高熱穩定及高反射歐姆接觸電極之研究

Low Resistance, High Optical Reflectivity and High Thermal Stability Ohmic Contacts Applied for Flip-chip Ultraviolet Light-emitting Diodes

潘昌吉(Chang-Chi Pan) ； 陳冠廷(Guan-Ting Chen) ； 陳銘勝(Ming-Shung Chen) ； 方啟鑫(Chi-Shin Fang) ； 綦振瀛(Jen-Inn Chyi)

《光學工程》 90期 (2005/06) Pp. 1-9

https://doi.org/10.30011/OE.200506.0001

摘要

Low contact resistance, high reflectivity and high thermal stability multilayer ohmic contacts to n and p-type GaN for flip-chip ultraviolet light-emitting diodes have been demonstrated. For n-type ohmic contacts, specific contact resistivity as low as 1×10^(-6)Ω-cm^2 is obtained using a metallization scheme of Ti/WSi0.05/Ti/Au (20/40/20/200nm) after thermal annealing at 800℃ for 3min in N2 ambient. Its specific contact resistivity maintains at the same level after heat treatment at 300℃ for 96 hours. Its optical reflectivity in the wavelength range of 350 to 450nm is about twofold higher than that of the conventional Ti/Al/Ti/Au (30/100/40/120 nm) contact. The former also exhibits much smoother surface and better edge acuity, which is essential for devices sensitive to critical dimension control. For p-type contacts, Pd/Ni/Al/Ti/Au contact is able to retain its specific contact resistivity (＜2×10^(-2)Ω-cm^2) and reflectivity (＞76%) after a long-term annealing at 150℃ in nitrogen ambient. According to the secondary ion mass spectroscopy study, it is the Ni layer that prevents the penetration of Ti into GaN during thermal treatment and improves the thermal stability.

關鍵字

氮化鎵 ； 覆晶式紫外光發光二極體 ； 歐姆接觸

並列摘要

Low contact resistance, high reflectivity and high thermal stability multilayer ohmic contacts to n and p-type GaN for flip-chip ultraviolet light-emitting diodes have been demonstrated. For n-type ohmic contacts, specific contact resistivity as low as 1×10^(-6)Ω-cm^2 is obtained using a metallization scheme of Ti/WSi0.05/Ti/Au (20/40/20/200nm) after thermal annealing at 800℃ for 3min in N2 ambient. Its specific contact resistivity maintains at the same level after heat treatment at 300℃ for 96 hours. Its optical reflectivity in the wavelength range of 350 to 450nm is about twofold higher than that of the conventional Ti/Al/Ti/Au (30/100/40/120 nm) contact. The former also exhibits much smoother surface and better edge acuity, which is essential for devices sensitive to critical dimension control. For p-type contacts, Pd/Ni/Al/Ti/Au contact is able to retain its specific contact resistivity (＜2×10^(-2)Ω-cm^2) and reflectivity (＞76%) after a long-term annealing at 150℃ in nitrogen ambient. According to the secondary ion mass spectroscopy study, it is the Ni layer that prevents the penetration of Ti into GaN during thermal treatment and improves the thermal stability.

並列關鍵字

GaN ； flip-chip ultraviolet light-emitting diodes ； ohmic contact