掺杂GaN的湿法刻蚀研究

Research on Wet Etching of Doped GaN

对掺杂GaN的湿法刻蚀研究进行了总结,回顾了不同的湿法刻蚀技术,包括传统的酸碱化学刻蚀和电化学刻蚀。从掺杂GaN的生长过程、表面化学组分和光电性质出发,深入地分析了湿法刻蚀的特性,对比了不同刻蚀方法的原理和效果。考虑到p-GaN的表面氧化层比较厚,接触电阻较大,能带向下弯曲不能进行光增强湿法刻蚀,重点阐述了p-GaN的传统湿法刻蚀和n-GaN的紫外光增强湿法刻蚀技术。与传统化学刻蚀相比,光增强湿法刻蚀具有更为广阔的前景。结合GaN基半导体器件的制作,对湿法刻蚀的主要应用进行了较为详细的归纳。目前,湿法刻蚀和干法刻蚀可以有效结合。将来湿法刻蚀有希望代替干法刻蚀。

Studies of wet etching of doped GaN are summarized and various wet etching techniques are reviewed, including conventional chemical etching in aqueous acid or base solutions and electrochemical wet etching in electrolytes. Properties in wet etching of doped GaN is deep analyzed on the basis of growth conditions, surface chemical composition, optical improvement and electrical character. The mechanism and effect of each etching process are discussed and compared. Considering some factors of p- GaN, including comparatively thick surface oxide layer, relatively big ohmic contact resistance and failed ultraviolet enhanced wet etching caused by downward band-bending at the p-GaN/electrolyte interface, the traditional wet etching of p-GaN and ultraviolet enhanced wet etching of n-GaN are expounded em- phatically. Ultraviolet enhance wet etching has greater potential than conventional wet etching. The main applications of wet etching are summarized in detail combining with the fabrication of GaN-based semiconductor devices. At present, wet etching complements dry etching effectively. In the future, wet etching can be expected to replace dry etching.