Of Sio <sub>, 2 </ Sub> Glass Of Semiconductor Nanocrystals And Radiation Effects Research

Owing to their unique optical and electronic properties, semiconductor nanomaterials have attracted much attention in recent years, and had a great potential application in non-linear optical devices, functional material, etc. Fused silica, as a useful optical material, has been used in optical fiber and other optical devices. The research of germanium has an important application background as a typical semiconductor. The optical properties of the composite structure, Ge-SiO₂, have attracted much attention, especially the luminescence.In this work, the optical absorption spectroscopy, Photoluminescence (PL) measurements, transmission electron microscopy (TEM), atomic force microscope (AFM) measurements, X-ray photoelectron spectroscopy (XPS) and TRIM 96 calculation code had been utilized to characterize the optical and structural properties of samples. The results have been listed as follow:1) Ge nanoparticles formed after 56-keV Ge⁺ ions were implanted into fused silica up to a dose of 1×10¹⁷cm² at room temperature. The Ge nanocrystals distribute near the surface of the fused silica. The ion implantation had induced many defects. As a result, the UV absorption increased, but no peak appeared.2) After annealing in O₂, N₂ and Ar ambience, the absorption edge shifted to the higher energy due to the decrease of defects density with the increase of annealing temperature. The absorption peak of GeO at 240nm appeared after annealing in O₂ ambience. After annealing in N₂ ambience, a new absorption peak at 418nm appeares, and we have attributed this absorption peak to the Si-N composite.3) After annealing in different ambience, two PL bands at 294nm and 386nm induced by GeO center were observed, respectively. The PL bands of samples annealing in O₂ ambience is more intensity than others. During the annealing, Ge atoms near the surface migrated outside. At the same time, the Ge atoms inside congregated and growed up. After annealing at 1000℃, a large amount of Ge atoms migrated out of the crystals.4) Ge⁰, GeO and GeO₂ coexisted in the implanted sample. After annealing at 600 ℃, its charge state did not change. After annealing at 1000℃, GeO₂ was decomposed into GeO because GeO is the most composite among the germanium oxides. However, there was still some Ge⁰ existed in the crystals.5) N⁺ ion irradiation of Ge⁺-implanted samples was conducted at energy of 60 keV and then annealing in Ar ambience. The absorption edge shifts to the high energy side, and the PL of GeO defect at 294nm, have been detected after irradiation. There were obviouse dislocation loops in AFM images. The germanium is in charge state of Ge⁰, GeO and GeO₂ after irradiation. Same as the samples after annealing in N₂ ambience, a new absorption peak at 418nm appeared after annealing at 500℃, achieved the greatest after 550℃annealing, and disappeared after 600℃annealing, caused by Si-N compound(Si₃N₄ or SiO_xN_y).6) The defects induced by Ge ion implantation decreased after irradiation with 1.064μm laser beam at energy of 100mJ/cm². The irradiation defects and ripple induced by fusion of laser irradiation had been detected. After irradiation the surface of sample became smoother and the absorption edge shifted to the higher energy. Only the PL peak at 294nm had been detected after laser irradiation.