Loss Of Interstitial Oxygen Research Articles

High-temperature phase transformation of oxidized R 2NiO 4+δ(R=La, Pr and Nd) under vacuum

The structural behaviour at high temperature of the oxidized nickelates R 2NiO 4+δ(R=La, Pr and Nd) has been studied by means of neutron diffraction measurements. In the case of La 2NiO 4+δ the structure has tetragonal symmetry for the full measured temperature range. The temperature dependence of a and b cell-parameters shows the existence of a first order structural transformation, from an orthorhombic symmetry at room temperature, to a tetragonal symmetry at higher temperatures for Pr and Nd compounds. The value of this transformation temperature is about 690 K in the case of Pr 2NiO 4+δ and 790 K for Nd 2NiO 4+ δ. In the latter case, keeping the sample under vacuum (∼10 −6 Torr) at a temperature around 1100 K, the structure becomes again orthorhombic, but different from the previous one. This effect is due to the loss of interstitial oxygen from the system at constant high temperature with the time.

Depth profiles of thermal donors formed at 450 degrees C in oxygen-rich n-type silicon

Depth profiles of thermal donors formed at 450 degrees C in oxygen-rich n-type silicon have been studied through capacitance-voltage measurements of Au Schottky diodes in the oxygen concentration range 8.1*1017 to 15.3*1017 cm-3. Thermal donor concentrations increase with depth and their depth profiles are empirically fitted to the error function equation. The obtained diffusivity decreases with annealing time and is higher for samples with lower initial oxygen concentrations. Combining with the infrared absorption measurements, it is found that the curves of the diffusivity as a function of loss of interstitial oxygen coincide with each other. A similar tendency is observed for the oxygen diffusivity evaluated with secondary-ion mass spectrometry. These results indicate that depth profiles of thermal donors are caused by both the out-diffusion and clustering of oxygen.

Depth Profiles of Thermal Donors in Czochralski-Grown N-Type Silicon

ABSTRACTDepth profiles of thermal donors introduced by heat treatment at 450°C in Czochralski-grown n-type silicon have been studied through capacitance-voltage measurements of Au Schottky diodes in the oxygen concentration range 8.1×1017 to 15.3×1017 cm3 Thermal donor concentrations increase with depth and their depth profiles are fitted to the error function equation. The obtained diffusivity decreases with annealing time and is higher for samples with the lower initial oxygen concentrations. Combining with the infrared absorption measurements, it is found that the curves of the diffusivity as a function of loss of interstitial oxygen coincide with each other. The similar tendency is observed on the oxygen diffusivity evaluated with secondary ion mass spectrometry. These results indicate that the oxygen diffusivity at 450°C is related to both the outdiffusion and clustering of oxygen. Depth profiles of thermal donors formed at 650°C are also reported.

Enhanced thermal donor formation and oxygen diffusion in silicon exposed to a hydrogen plasma

Czochralski (CZ) silicon has been heated in a hydrogen plasma. The rates of production of thermal donors and the rate of loss of interstitial oxygen from solution are enhanced compared with conventional furnace anneals. Other gas plasmas produce somewhat smaller enhancements. There is no evidence for a large flux of point defects from the surface. Secondary ion mass spectrometry (SIMS) measurements show that hydrogen is not present in high concentrations throughout the bulk of the samples, but it could act as a catalyst to enhance the oxygen diffusion rate.

Do oxygen molecules contribute to oxygen diffusion and thermal donor formation in silicon?

In- and out-diffusion experiments of oxygen in silicon indicate the existence of an oxygen-containing species diffusing much faster than interstitial oxygen at temperatures below about 700°C. The formation of oxygen-related thermal donors in the temperature range around 450°C also requires a fast diffusing species. The paper examines the possibility of this fast diffusing species beingmolecular oxygen, as had been suggested earlier. Special emphasis will be placed on experimental results which have become available since that time. These results allow one to relate thermal donor formation to the loss of interstitial oxygen and to oxygen precipitation. The role of carbon is also considered in this context.

Early stages of oxygen precipitation in si: morphology and structure

Intrinsic gettering in Si - VLSI technology depends on a controlled initial stage of oxygen precipitation and is characterized by a complicated interaction of growth-induced microdefects, self interstitial (SiI) generation and strain caused by SiO2 precipitate growth and secondary defects, table 1. We address the controversial issues of the identity of ribbon-like defects (RLDs) and of the nature of oxygen precipitate nuclei.RLDs were initially identified by HRTEM as coesite, a high pressure phase of SiO2. Recently, both Bourret and Reiche et al have interpreted the RLDs as hexagonal Si, or agglomerates of Si. We wish to make the point that the evidence against coesite is, as yet, not conclusive, and present circumstantial evidence in favour of coesite: (1) The loss of interstitial oxygen correlates with the density of RLDs (Fig. 1) at 450 - 485°C.