光照强度和掺杂浓度对多孔硅形貌和电化学行为的影响

Effect of Illumination Intensity and Doping Concentration on the Morphology and Electrochemical Characteristics of Porous Silicon

测试分析了光照强度和掺杂浓度对n型硅电极电化学特性的影响。采用电化学阳极腐蚀法在光照辅助下制备多孔硅(PS),通过扫描电镜研究掺杂浓度对PS表面微观形貌的影响,通过积分球测试仪测试研究了PS对光的反射率。结果表明,对于n型硅,光照是激发空穴的必要手段,光照强度越强,硅/电解液界面的电荷转移阻抗越小,更利于反应的进行;掺杂浓度越高,电化学极化阻力越小,促进PS孔密度增加。本实验条件下,形成的PS是微米级孔,随着掺杂浓度的增加,形成的PS孔径越小,孔深存在一个极值;电阻率为0.35Ω·cm的硅片拥有最大的孔深13μm;PS的孔结构大大提升了硅基对光子的捕获能力,相比于单晶硅,在可见-近红外范围,电阻率为0.0047Ω·cm的硅片制备的n-PS对光的反射率已经从30%降低到了5%。

The electrochemical characteristics of Si-electrode affected by illumination intensity and doping concentration were studied. Porous silicon( PS) was prepared on monocrystalline silicon wafer substrate by electrochemical etching under the light-assisted. The SEM was used to observe the microstructure of the PS prepared under different doping concentration. The integrating sphere detector also was used to test the luminous reflectance of the PS. The results showed that illumination is necessary for the n-type silicon,and the greater of the illumination intensity,the smaller of the electronic transfer impedance,the reaction become more easily; the PS hold micron sized pore,and with the increase of the doping concentration,the diameter of the pore become much smaller. There is a maximum value of the pore depth. In this study,the best one is 13μm in the resistivity of 0. 35Ω·cm. The ability of capturing photon is improved with the help of the porous structure of the PS. Compared with the monocrystalline silicon,the luminous reflectance had been decreased from 30% to 5% in the scope of visible to near-infrared.