The study of metal contacts on p-GaN

• Main Authors: Chiung-chi Tsai, 蔡炯棋
• Other Authors: Chen-Shiung Chang
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/65029005664540465097

碩士 === 國立交通大學 === 光電工程所 === 87 === In this dissertation , severial kinds of metal schemes were used to form ohmic contacts on p-GaN. In this work ,ohmic contact to p-type GaN with the lowest contact resistivity of 9.6 × 10－4Ωocm2 was developed by the surface treatment prior to Pd/Au metal deposition. Compared the metal schemes of AuZn/Ni/p-GaN andAu/Ni/p-GaN.It is observed that the Ni dissociates at the p-GaN surface and this dissociation promotes the Zn diffusion upon heat treatment.So the existance of Zn does effectionlly lower the contact resistivity(1.03 × 10-2Ωocm2). Investigation new metal scheme of AuBe/Ni to p-GaN have been carried out.It is observed that the contact resistance drastically increase as the annealing temperature excess 550℃.This result indicated that the diffusion of Be atoms into the p-GaN layer would increase the resistance of the layer.The behavior of the Be atoms in the p-GaN layer would be like as a lattice defect, such as interstitial impurities.To explore the origin of Be atoms in the p-GaN layer.The PL measurements were performed at 10K.The emission(3.17eV) of DAP is attributed to the shallow donors level(at about 30meV below the conduction band) and the Be-related deep level impurities(at about 262meV above the valence band)