Hi jie bai,
You should do a deoxidation with HCl:DI 1:2 for 1 mn  dry your wafer with
Azote just before the metallization and placed it immediately in the
chamber. Another solution depend on the machine that you are using you can
do a rapid dry etching in the chamber before the metallization.
Hope that you will resolve your problem.

Abdou


>From: "jie bai" 
>Reply-To: General MEMS discussion 
>To: 
>Subject: [mems-talk] stick Ni/Au on p-GaN
>Date: Thu, 15 Jun 2006 15:40:14 +0100
>
>Hi, I am doing Ni/Au on p-GaN as p-contact and Ti/Au as bondpad. But the
>whole layer including Ni/Au and Ti /Au is always peeled off when I am doing
>wire bonding. I think it is the adhesive problem between Ni/Au and p-GaN.
>Can you give me suggestion ? By th way, I have tried Asher before
>depositionbut the resistance is increased. So I hope to get rid of the
>ashing. Thanks.