The Study Of Formation Mechanism And Properties Of Nano-scale Islands On The Surface Of Low-dimension Alloy

Along with development of modern electronic science and technology, the integration degree of the electronic devices increases year-by-year. The density of the transistor comes up to a incredible height according to Moore law. The modern electronic devices have become miniaturization gradually and it needs advanced material processing technologies and preparing techniques in order to realize miniaturization of the devices. The development of thin film science and technology supplies material foundation for new-generation electronic technology, especially in the research of nano-scale low dimension material. For instance, the super lattices and quantum wells of two-dimension semiconductor, one-dimension quantum wires and zero-dimension quantum dots, have obtained delightful achievement.In our paper, we firstly prepared the pure indium thin film with DC magnetic sputtering technique. According to SEM images, we found when the sputtering power and deposition time were low, the surface of the indium film was smoothness and orderliness, and the morphology of indium film surface was maze. Along with deposition time increased, the surface of the film became rough from smooth gradually and there were many hillocks formed in the surface. The hillocks would grow up with the continual increase of indium deposition time. If the sputtering power increased to a certain volume, the hillocks disappeared and the roughness of the surface enhanced. Via TEM results, the hillocks were formed by conglomeration of several grains and the amalgamation of the grains resulted in new hillocks formation. According to the XRD results, we also found the intensity ratio of the non-preferred facet (002) of the indium increased. We eventually found the preferred growth of the non-preferred facet (002) was due to release of the interior compressive stress which enhanced during deposition process of the indium film. In the same time we found when the deposition power was up to 25W, there were many nano-scale rods formed in the surface of the indium film. We gained the similar results form the pure indium films prepared by the RF magnetic sputtering.Afterwards, we prepared the indium film with Au as a buffer layer with DC magnetic sputtering and RF magnetic sputtering technology respectively. According to the SEM results, we found there were a lot of nano-islands formed in the surface of the indium film. The size and distribution of the indium islands were deeply relative with the deposition time, sputtering power, the temperature of the substrate, the pressure of Argon and the thickness of the Au buffer layer. Via analysis of XRD and TEM results, we noted the structure of indium islands were body-center tetragonal. There was a alloy layer between the Au buffer layer and indium film and the lattice structure of the indium changed. The indium islands distributed uniformly and the size distribution was narrow. Compared the two films prepared with different methods, we found the difference of morphology of the pure indium film and indium film with Au buffer layer was ascribed to distinct mechanism. The growth mode of the pure indium formation belonged to S-K film growth mode, and the formation of the indium nano-hillocks resulted from the interior compressive stress in the film. In the indium film with Au as buffer layer, there was a alloy layer of Au and indium- Au3In2-formed between the Au buffer layer and indium film. The Au3In2 alloy layer changed the original wetting substrate into a non-wetting substrate. The non-wetting substrate resulted in the indium island forming with V-W growth mode. We could change the size and distribution of the Indium islands by controlling the parameters of the experiments.We choose a indium island sample with Au buffer layer and kept it 500℃in the air for 5 hours. The indium islands changed into In₂O₃ nano-structure material system. We noted the morphology of the In₂O₃ islands did not change greatly compared with original Indium islands from the SEM results even though the annealing temperature exceeded the indium melting point more. From the XRD pattern, we found the alloy layer Au3In2 changed into Au10In3 and the structure of In₂O₃ islands were Bixbyite Mn2O3 type with the lattice constant a = 1.012 nm. After analyzing the EDX data, we find that the atomic ratio of indium and oxygen are 44:56. Clearly, the oxygen atoms were deficient in the nano-structures. The PL of the In₂O₃ nanohillocks is studied at room temperature using a Ne laser excitation at 280 nm. We find that broad PL emission spectra appear for In₂O₃ nanohillocks at 420 nm and 470nm with a shoulder at 450 nm under the excitation at 280 nm. The mechanism of the photoluminescence was due to the ionized oxygen vacancies.