Ultra-Shallow Doping of GaAs with Mg, Cr, Mn and B Using Plasma Stimulated Room-Temperature Diffusion

It is demonstrated that Mg, Cr, Mn and B can be doped close to GaAs surface by plasma doping without external bias at room temperature (RT). The process only takes a few minutes, and impurity densities in the range of 1018–1021/cm3 can be achieved with doping depths about twenty nanometers. The experiment results are analyzed and the physical mechanism is tentatively explained as follows: during the doping process, impurity ion implantation under plasma sheath voltage takes place, simultaneously, plasma stimulates RT diffusion of impurity atom, which plays the main role in the doping process. The enhanced RT diffusion coefficients of Mg, Cr, Mn and B in GaAs are all in the order of magnitude of 10-15 cm2sec-1. This is reported for the first time among all kinds of plasma assisted doping methods.

The Study of Surface Morphology and Roughness of Silicon Wafers Treated by Plasma

Plasma is generally used for the doping of semiconductors. During plasma doping process, plasma interacts with the surface of semiconductor. As a result, defects are induced in the surface region. In this work, the surface morphology and roughness of silicon wafer caused by plasma treatment is studied by use of atom force microscope (AFM). It is found that, during the plasma process, each of the processing time of plasma, location of silicon wafer in plasma and the way of placement of silicon wafer has an influence on the surface morphology and roughness and the reason is discussed. The interaction between plasma and the surface of silicon wafer is qualitatively discussed.