【作者】 申慧娟；

【导师】 胡陈果； 廖克俊； 刘爱民；

【作者基本信息】 重庆大学 ， 凝聚态物理， 2006， 硕士

【摘要】 用电化学方法制备纳米多孔阵列具有操作简单、成本低廉和低损伤等优点,生长的孔的尺寸可以在纳米和微米量级之间变化。早在1990年,人们就已经用这种方法制备出了多孔Si。在它的激励下,越来越多的目光也开始转向了Ⅲ-Ⅴ族化合物半导体,因为他们具有很高的载流子迁移率和特殊的光学性质等。但是刻蚀Ⅲ-Ⅴ化合物半导体要比Si复杂的多,至今还没有完全理解其形成机理。本文选择半导体InP作为研究对象,因为InP具有很多优于GaAs的性质。实验发现在不同条件下可以产生不同的多孔结构,可以预见,如果刻蚀条件选择适当,就会形成规则的纳米多孔阵列。本文发现大多数刻蚀后的样品,大孔层的上面往往被一层微孔覆盖,这种微孔的孔径要比大孔小的多。本文对样品表面预留划痕并进行刻蚀,发现刻蚀后,有划痕的部分比完整样品表面优先出现大孔。文中对这种情况进行了分析,表明表面预处理对刻蚀初始位置的影响很大;还发现在一定条件下形成的孔壁存在侧蚀现象,某些孔壁还表现出:随着孔深增加,孔壁较为光滑,侧蚀程度明显减小的特征。文中对此进行了分析,有望得到具有光滑孔壁的多孔阵列。本文通过对不同掺杂浓度的样品进行刻蚀,发现重掺杂的样品刻蚀出的孔在深度和孔径上都比中度掺杂的大。本文研究了刻蚀中出现的电流振荡现象。实验发现在电压较大的时候,存在电流的周期性振荡,其振幅随着外加电压的增加而增大;当外加电压小于1.3V时,大幅度振荡不会出现。除了大幅度周期性振荡外,在每个大幅振荡之间还有一些混乱的小幅振荡。文中通过对比典型的I-t曲线和刻蚀形貌,对这种大幅振荡和小幅振荡分别运用V. Lehmann和Jens模型成功地进行了分析。更多还原

【Abstract】 Electrochemical etching, which has the features of low temperature, low damage, simplicity and low costs in the etching process, can be used to prepared nano-materials. With this method, porous silicon had been prepared in the early 1990s. Motivated by the study of porous silicon, lots of researchers have been attracted by porous compound semiconductors due to their high carrier mobility and some specific optical properties. However, the etching process ofⅢ-Ⅴcompound materials is more complicated than that of Si, and the mechanism of the etching has not been understood yet.In this paper, we choose the InP as the material to study its electrochemical etching process for its priorities compared to GaAs. It has been found that porous structure is varied with etching conditions, indicating a possibility of regular pores array if the optimal condition could be used.We also found that most macropores layer of the etched samples usually covered by micropores layer with minute diameters, whose pore-size can be far more different from macropores layer’s. Comparing the pores formation on scratched surface with intact surface of samples, we found macropores imaged prior to the former one, showing that the preprocessing is important to define the pores initial position. The reason is given in the paper. It is also found sometimes branchs appear in many samples, and the smooth degree of pore wall increases with the pores deepening,demonstrated the possibilities of pores arrays with smooth wall if optimal condition is offered. This is analyzed in the paper.Further more, the etching of samples with different doped concentrations are studied. It is found that pore’s depth and diameter on n-InP with heavily doped concentration is larger than moderately doped samples.Finally, we discussed the current oscillation in etching process. At constant voltage condition, the periodical current oscillation is observed in the experiment, and only appears at the voltage larger than 1.3V. The amplitude increases with the imposed voltage. During the oscillation in large amplitude, there are many random small amplitude oscillations. Comparing the cross section SEM of pores with the I-t curve, large oscillation unexpectedly coincident with porous layer, we analyzed the large and small oscillation based on V. Lehmann and Jens models, respectively.更多还原