The Study Of Porous InP Formed By Electrochemical Etching

Electrochemical etching is a convenient method to get micro-structure with simple equipment. Many kinds of micro structures with size from tens of nanometers to several micrometers may be obtained by the simple method. For example, combining electrochemical etching and photolithography, regular Si structure with any shape can be obtained which can be used in Micro-Electro-Mechanical Systems (MEMS) and integrate circuit (IC). Inspired by the electrochemical etching of silicon people started to study porous III-V semiconductors from about ten years ago. Up to now, a lot of delightful results have been obtained.The dissertation will discuss the electrochemical etching of InP which is a kind of III-V semiconductor. Through experimental study, we got many different porous structure of InP including prick arrays, M-shape pores, triangle pores and quadrate pores. Different structures are formed at different conditions which will be discussed emphatically.Periodical current oscillation was observed when InP was etched under constant voltage. With further study we found that the current oscillation corresponded with the porous structure of InP sample. We explain the periodical current oscillation with oxide layer model developed by Lehmann and an air bubble theory. Besides, each long current period contains many small irregular current oscillations. According to the explanation of H. Fo|¨il et al. the irregular current oscillations was duo to interactions among pores. We also studied the change of the current with voltage and found that a large voltage is necessary for the periodical current oscillation. A periodical current oscillation will result in abnormity of etched InP sample. However, when anodization voltage was below 1.3 V, side-etching would occur. We discussed the side-etching phenomenon in the dissertation.