Palladium membranes have been used for decades for the separation of hydrogen from other gasses. In this letter the use of thin palladium leaves to act as sources of atomic hydrogen for silicon samples is explored. It has been assumed in the past that although hydrogen diffuses through palladium in atomic form, the atoms recombine to form molecular hydrogen at the surface. In this letter it is shown that hydrogen supplied to one surface of a palladium leaf can result in atomic hydrogen being released from the opposite surface at low pressure. This is demonstrated through the use of a palladium leaf in a direct plasma system which allows for atomic hydrogen to be supplied to a sample while avoiding exposure to UV radiation from the plasma and high energy charged particles. This method is shown to provide significant atomic hydrogen to silicon samples and improve passivation of silicon surfaces.
Method of Shielded Hydrogen Passivation: Schematic of direct plasma chamber with a shield inserted between the plasma and the silicon sample.
A new technique is described by which ionic species can be rapidly transported into oxide films, and once there provide effective and stable field effect passivation to silicon surfaces. Field effect passivation in thermally grown oxide films has been achieved by embedding potassium ions using a combined drift and diffusion mechanism at high temperature. This process has been shown to be over 10 times faster than a pure diffusion process. The resulting passivation stable for periods exceeding 600 days, with lifetimes reaching 1.4 ms, equivalent to a surface recombination velocity (SRV) ≤ 5.7 cm/s, on 1 Ωcm, n-type, FZ-Si.
Gases make up one of the standard topics in high school chemistry, and several experiments on gases are done in the student laboratory. These studies include the laws of Boyle and Charles, the general gas law applied to molar volume or reaction quantities (with the partial pressure law), and effusion rate studies. The determination of oxygen in air is not a common
The strength of bonds between atoms in metals, the relative ease of removing electrons from atoms, and the energy lowering of the attraction of water molecules for positive ions in solution all aid beginning student's understanding of why reactions occur.
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