The Study Of Porous InP Formation By Electrochemical Etching And Related Mechanism

The electrochemical technique is a cheap and simple method to fabricate the porous semiconductor materials. Over the past several decade, most of efforts were concetrated on the formation and mechansim of porous Si, however, the electrochemical technique to date has not been widely used to etch III-V compound semiconductors because this technique is not mature. In addition, the mechanism of the reaction and the formation of the porous structure are unclear.The mechanism and formation of porous InP are explored by electrochemical etching in the thesis. The electrochemical technique is used to fabricate the porous InP, mico- and nano-sized of InP structure in the different electrolytes. These structures are characterized by SEM (Scanning Electron Microscopy). The production is obtained by etching in the neutral NaCl solution, which is characterized by EDX (Energy Dispersive X-ray Analysis) and XRD (X-Ray Diffraction). And then the mechanism of the reaction in the different electrolytes is discussed, at the same time the formation of the porous InP, the micro- and nano- size structure of InP is also analyzed. The main results obtained in this thesis are as follows:1. InP is etched by electrochemical technique in the strong HCl solution. The microrods and microtips of InP were prepared in HCl solution. The formation of the microrods and microtips of InP is analyzed. We considered that the V-grooves were firstly formed due to the effect of surface curvature, and then the microrods were formed. The formation of the microtips was ascribed to the excessive etching in the process.2. NaCl and NaF solution are used as the electrolytes based on the basis theory of the electrochemical process. The potential of the anodization in two kinds of the electrolytes is studied by linear sweep voltammetry. And the two-dimensional(2D) and three-dimensional(3D) porous structure of InP have been fabricated by electrochemical method in the two kinds of the electrolytes, respectively. The regular 2D porous InP was obtained in the NaCl solutions, and the 3D porous InP was realized in the NaF solutions. The reaction mechanism of the eight holes is confirmed based on the EDX and XRD for the production. The reaction mechanism and the equation of electrochemistry in the neutral electrolytes are proposed. The formation mechanism of porous InP with different structure is discussed combining surface curvature model for porous Si with surface state, and characteristics of InP wafers.3. The porous InP is also obtained by cathodic decomposition.The current oscillatory phenomenon is due to the effect of the gas in the case. During cathodic decomposition of InP, the pores partially filled with the gas, resulting that one-side of pores is protected. Eventually, the porous structure of InP with the side pores interconnected is formed.4. The ZnO thin film is formed by electrochemical deposition on n-InP(100) wafers.