화합물 반도체내의 불균일성의 영향에 대한 연구

Abstract

In this paper, it has been investigated that 1) how to estimate several types of disorders, 2) What is the origins of disorders. It has been discussed in terms of optical, electrical, and structural properties. The purpose of this thesis is to control and reduce the disorders in semiconductors to improve the semiconductor device performance up to theoretical limits.

In the chapter 1, several types of disorders occurred due to three origins are introduced and the importance of the evaluation of those disorders is explained. In the chapter 2, the principles of photoluminescence spectroscopy, high resolution X-ray diffraction and Hall effects measurement are explained. In the chapter 3, Zn1-xCdxSe triple quantum wells are investigated. The PL linewidth broadening is analyzed from the point of the disorder induced inhomogeneous broadening. The calculated results from theoretical models related to composition and interface disorder strongly corresponding to experimental values. However, it was found that in the case of high Cd-content alloys the Cd inter-diffusion acts as an additional origin for PL linewidth broadening. In the chapter 4, Zn1-xCdxTe multi quantum wells are investigated in terms of PL linewidth broadening due to interface and composition broadening. The results indicate that although disorder can be minimized by the optimization of growth conditions, in a QW with very thin QW thickness, disclose of an exciton wave function will make an additional PL linewidth broadening. In the chapter 5, the structural qualities of GaN films are investigated using HRXRD measurement. Structural disorders including mosaicity, tilt, twist and bowing are evaluated using X-ray rocking curve. Also, the surface-damage layers induced from structural disorder is removes by chemical etching. From these results, it is found that the structural disorders can be an origin of structural defects. In the chapter 6, electrical properties of GaN film grown on AlN buffer is investigated using temperature-dependent Hall effect measurement. The results indicate that the defects originated from disorders have a large influence on the electrical transportation of semiconductors. In the chapter 7, based on the results obtained from this thesis are summarized and concluded.