P型氮化鎵之歐姆接觸研究
Study of Ohmic Contacts on P-type GaN
Date Issued
2005
Date
2005
Author(s)
Lin, Jian-Ji
DOI
en-US
Abstract
We have discussed two kinds of the p-GaN ohmic contacts: Ni/Au and Ni/Au/ITO ohmic contacts. After thermal annealing at proper temperature, both contacts show ohmic characteristics. Ni diffuses out of the interface and reacts with O2 forming NiO after RTA. Au diffuses into GaN matrix and forms Au-Ga solid solution which helps the generation of Ga vacancies. The Ga vacancies act as acceptors in p-type GaN. With a large amount of Ga vacancies the surface p-type GaN becomes p+-GaN which results in the depletion region narrowing and SBH reduction. Ohmic contact on p-type GaN is then obtained.
In Ni/Au/ITO system, In atoms in ITO may form alloy with Au and leading to the reduction of the contact work function since the work function of In is low. During ITO sputtering, the ITO atoms with high energy could damage the thin Ni/Au film which is already deposited on the GaN. Thus the Ni/Au/ITO shows poorer specific contact resistivity as compared with Ni/Au. But with much better transmittance and good conductivity for current spreading, Ni/Au/ITO is still a candidate of p-type GaN for LED fabrication.
Subjects
氮化鎵
歐姆接觸
氧化銦錫
GaN
ohmic contact
ITO
Type
thesis
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