Theoretical And Experimental Research On Gallium Arsenide Nanowire Pn Junction

The research work is mainly supported by the grants from National Basic Research Program of China (No:2010CB327601)-Basic Research on Compatible Heterogeneous Integration and Functional-Microstructure Assemblage for the Development of Novel Optoelectronic Devices, Program of Key International Science and Technology Cooperation Projects (No:2006DFB11110), The 111 Project (B07005), New Century Excellent Talents in University (No:NCET-08-0736), Chinese Universities Scientific Fund (No:BUPT2009RC0410), Changjiang Scholars and Innovative Research Team in University, MOE (No: IRT0609).Semiconductor nanowires are ideal building blocks for functional nanoscale device. Nanowire doping is the necessary step for fabrication of nanoscale device. However, systematic studies on reliable and well-controlled doping are still lacking for semiconductor nanowires. In this thesis, a great deal of work is demonstrated about theorical and experimental research on p-type doping, n-type doping,Ⅰ-Ⅴcharacteristic, pn junction of Gallium arsenide nanowire. The main achievements are listed as follows:1. In theory, we explain Zn element's impurity type in GaAs and draw the common p-type and n-type impurity's energy level diagram. It is summarized about p-type doping method and research results in foreign literature.2. In the first series of experiments, we study the effect of DEZn flow (80,40,lsccm) on the properties of the p-type GaAs nanowires and discover that due to reducing DEZn flow nanowire morphology change from bending to vertical. The reason for equal height growth of well-grown nanowire is analyzed and the TEM test is carried out to prove its zinc-blende structure.3. In highⅡ/Ⅲratio, there are two possible reasons influence on the bending of p-GaAs nanowires:(1) excess Zn atoms may segregate on the sidewalls forming deformation area; (2) surface stress and surface elasticity effects. By comparing Zn concentration kinking before and after, it can be proved that (1) is the primary reason for bending.4. Under different SiH4 flow (80,40sccm), n-GaAs nanowires are grown by metal-organic chemical vapor deposition on GaAs (111) B substrate. By comparison of Sample A and B's diameter, length, and growth rates, it can be concluded that SiH4 flow has less influence on the morphology of n-type nanowires. One possible reason may be that the solubility of Si in the Au particle is much lower than for Zn in the selected growth parameters.5. In terms of theory, the manufacture of ohmic contact is to combine heavy doping semiconductor with metal. The n-GaAs nanowire electrode fabrication scheme is designed and the electrode post-craft disposal is completed.Ⅰ-Ⅴcharacteristic is measured and the results are the forward opening voltage is 0.5V and the backward breakdown voltage is-1.5V.