Sodium dodecyl sulfate (SDS) effects at the electrified p- and n-GaAs(100)/H₂SO₄ interfaces were investigated by EIS, XPS and AFM. XPS data revealed that under the open circuit conditions, SDS adsorption on GaAs(100) results in a protective overlayer which prevents the further oxidation in air of both types of semiconductor surfaces. The dopant nature is, however, decisive for the way of bonding the surfactant molecule to the surface. At the p-doped substrate, SDS adsorbs mainly at As sites by its hydrocarbon tail and by the anion head to the Ga sites at the n-doped one. Although the surfactant behaves as a dipole under the applied potential control, the dopant type plays a key role in the SDS interaction with GaAs(100) electrodes too. EIS data evidenced that SDS interaction with n-GaAs(100) electrode brings a pronounced decrease of the capacitive contribution of the surface states and a shift of the flatband potential to less negative values, unlike the p-doped one, where no significant change in its electronic properties was observed. These results were rationalized in terms of surface states- and field-effects operating at the electrified interfaces under discussion.

中文翻译：

---

十二烷基硫酸钠溶液中GaAs（100）电极的表面状态和场效应

十二烷基硫酸钠（SDS）在带电的p-和n-GaAs（100）/ H ₂ SO _{4上的作用}EIS，XPS和AFM对接口进行了调查。XPS数据显示，在开路条件下，SDS在GaAs（100）上的吸附会形成保护层，该保护层可防止两种类型的半导体表面在空气中进一步氧化。然而，掺杂剂的性质对于将表面活性剂分子结合到表面的方式起决定性作用。在p掺杂的衬底上，SDS主要通过其碳氢化合物尾部和阴离子头在As位置吸附到n掺杂的Ga位置。尽管表面活性剂在施加的电势控制下表现为偶极子，但掺杂剂类型在SDS与GaAs（100）电极的相互作用中也起着关键作用。EIS数据表明，SDS与n-GaAs（100）电极的相互作用显着降低了表面态的电容作用，并使平带电势移至较小的负值，这与p掺杂的情况不同，后者的p掺杂无明显变化。观察到其电子性质。在讨论中的电气化界面上，根据表面状态和场效应对这些结果进行了合理化。