Experimental Study On The Doping And Composition Modulation Phenomenon Of InP-based Materials

?-?semiconductor materials, such as InP and InGaAsP, have high electron mobility and large band gap, and the majority of them are materials with direct-transition band gap. Thus, they can be used to fabricate photoelectronic devices and semiconductor devices with high speed and high frequency, such as semiconductor laser, semiconductor optical amplifier and heterojunction bipolar transistor. The growth of semiconductor materials is an very important step in the process of fabricating devices. In the thesis, Metal-Organic Chemical-Vapor Deposition(MOCVD) is used to grow InP and InGa AsP, and the saturation and diffusion effect of doped InP and the composition modulation phenomenon of InGa AsP are studied.In the process of growing n-type InP, the epitaxial layer with good quality and uniform carrier distribution is obtained, which is consistent with our expectation. The saturation of Zn is very likely to occur when Zn doped p-type InP is grown. In our experiments, the Zn saturation is avoided by reducing DMZn flow rate. In addition, the diffusion coefficient of Zn is relatively large, which results in the Zn diffusion at the interface of p-type InP epitaxial layer. A steep distribution of carriers at the interface of p-type InP layer is achieved by decreasing the growth temperature and DMZn flow rate at the same time, and thus the Zn diffusion is suppressed effectively.When growing InGaAsP epitaxial layer by MOCVD, the results showed that composition modulation of InGaAsP occurred in the epitaxial layer. We studied the principle of this phenomenon, and analyzed the effect of the epitaxial layer thickness, composition of InGa AsP and growth temperature on composition modulation phenomenon through experiments. It indicates that the InGa AsP solid solutions with compositions in a specific range are unstable and the composition modulation always exist. Furthermore, composition modulation becomes stronger when InGa AsP epitaxial layer is thicker. In our experiments, the composition modulation becomes more serious with the increase of growth temperature, which is contrary to the theoretical results. We think this abnormal phenomenon is related to the strain. Increasing growth temperature leads to larger tensile strain, which results in the increase of composition fluctuation intensity. Thus the composition modulation becomes stronger. In addition, the photoluminescence spectra show that there is also serious composition modulation in the p-type InGa AsP solid solutions.