正十八硫醇钝化GaAs(100)表面特性研究

Passivation of GaAs(100) Surface by 1-Octadecanethiol

为了有效降低GaAs半导体表面态密度,提出了采用正十八硫醇(ODT,CH3[CH2]17SH)进行GaAs表面钝化的方案。首先,分别对GaAs(100)晶片进行了常规硫代乙酰胺(TAM,CH3CSNH2)钝化和正十八硫醇钝化,通过X射线光电子能谱(XPS)对比分析了钝化前后晶片表面的化学成分,然后利用光致发光光谱(PL)对正十八硫醇处理的GaAs(100)晶片进行了钝化时间的优化,最后通过扫描电子显微镜(SEM)测试了钝化前后的晶片表面形貌。实验结果表明:采用正十八硫醇钝化的GaAs(100)表面,相比常规硫代乙酰胺钝化方案,具有更低的氧化物含量和更厚的硫化层厚度;室温钝化条件下,钝化时间越长,正十八硫醇的钝化效果越好,但PL强度在钝化超过24 h后基本达到稳定,最高PL强度提高了116%;正十八硫醇钝化的GaAs(100)晶片具有良好的表面形貌,表面形成了均匀、平整的硫化物钝化层。数据表明正十八硫醇是钝化GaAs(100)表面一种非常有效的技术手段。

The use of 1-Octadecanethiol(ODT,CH 3[CH 2]17 SH)to prepare clean GaAs(100)surface with low surface state intensity was demonstrated.Firstly,the X-ray photoelectric spectroscopy(XPS)of GaAs(100)passivated by 1-Octadecanethiol and Thioacetamide(TAM,CH 3CSNH 2)was compared.Secondly,the ODT passivation time at room temperature condition was optimized by photoluminescence intensity(PL)method.Lastly,the surface morphology before and after passivation using scanning electron microscope(SEM)was discussed.Experimental results indicate that the GaAs(100)passivation using 1-octadecanethiol is shown to lead a lower oxide contamination and a higher sulfide thickness compared with the traditional passivation method of TAM.In the range of 0-24 h,the room-temperature photoluminescence intensity keeps a continuous enhancement with time extend,and the maximum enhancement is 116%than un-passivation one;SEM shows that GaAs(100)wafer has good surface morphology after ODT passivation.This indicates that the surface passivation of GaAs(100)using 1-octadecanethiol is effective.