Papers by Keyword: Hydrogen Passivation

Abstract: We studied the hydrogen passivation/depassivation of four types of intrinsic defects (EI5/6, HEI7/8, HEI9/10, and P6/7) in p-type and semi-insulating 4H-SiC by means of electron spin resonance (ESR) for examining the origin of career-lifetime-killing defects. We suggest that the HEI7/8 and P6/7 centers are the strongest candidate for the origin of the lifetime-killing defects.

Abstract: The kinetics of hydrogen penetration through dislocation networks produced by silicon wafer bonding are investigated by means of reverse bias annealing (RBA) procedure. By using the combination of capacitance-voltage (CV) profiling of net-acceptor concentration and deep level transient spectroscopy (DLTS) the total concentration of H introduced in the samples during wet–chemical etching at room temperature was defined. Two processes with the different time constants τ₁ and τ₂ was found for the bonded sample. The slow process τ₁ with an activation energy of (1.25±0.13) eV was analogous to that in the reference sample and corresponded to the dissociation of boron-hydrogen pairs. The fast process τ₂ was found to exhibit a lower activation energy of (0.87±0.25) eV and was identified as the release of hydrogen bound at screw dislocations by their elastic strains.

Abstract: The influence of the hydrogen content in the amorphous starting material on hydrogen bonding and defect passivation in laser annealed polycrystalline silicon is investigated. The samples are characterized using electron paramagnetic resonance and hydrogen effusion measurements. After laser dehydrogenation and crystallization the samples contain a residual H concentration of up to 8×1021 cm-3. During a vacuum anneal at least 1.5×1021 cm-3 are mobile of which only 3.7×1018 cm-3 H atoms passivate preexisting Si dangling bonds. It is shown that a vacuum anneal can cause the vast majority of H atoms to accumulate in platelet-like structures. Defect passivation and platelet nucleation and growth occur spatially separated requiring long range H diffusion.

Abstract: This study is focused on characterization of deep energy-level interface traps formed during sodium enhanced oxidation of n-type Si face 4H-SiC. The traps are located 0.9 eV below the SiC conduction band edge as revealed by deep level transient spectroscopy. Furthermore these traps are passivated using post-metallization anneal at 400°C in forming gas ambient.

Abstract: We studied the annealing process to improve the field-effect channel mobility (μFE) on the 4H-SiC (11-20) face. We found that wet annealing, in which a wet atmosphere was maintained during the cooling-down period to 600°C after wet oxidation, was effective. The interface states (Dit) near the conduction band edge decreased and the μFE increased up to 244 cm2/Vs. Furthermore, the origin of this high channel mobility was investigated using secondary ion mass spectroscopy (SIMS) measurement and thermal desorption spectroscopy (TDS) analysis. It was indicated that the hydrogen density at the MOS interface was increased by the wet annealing and the hydrogen was desorbed mainly at temperatures between 800 °C and 900 °C. These hydrogen desorption temperatures also corresponded to the temperatures of the μFE reduction by argon annealing after the wet annealing. These results indicated that this high channel mobility was achieved by hydrogen passivation during the wet annealing at temperatures between 800 °C and 900 °C.