High-resolution investigations of ripple structures formed by femtosecond laser irradiation of silicon

We report on the structural investigation of self-organized periodic microstructures (ripples) generated in Si(100) targets after multishot irradiation by approximately 100-fs to 800-nm laser pulses at intensities near the single shot ablation threshold. Inspection by surface sensitive microscopy, e.g., atomic force microscopy (AFM) or scanning electron microscopy (SEM), and conventional and high-resolution transmission electron microscopy reveal complex structural modifications upon interaction with the laser: even well outside the ablated area, the target surface exhibits fine ripple-like undulations, consisting of alternating crystalline and amorphous silicon. Inside the heavily modified area, amorphous silicon is found only in the valleys but not on the crests which, instead, consist of highly distorted crystalline phases, rich in defects

Avalanche breakdown in multicrystalline solar cells due to preferred phosphorous diffusion at extended defects

Multicrystalline solar cells break down strongly at reverse voltages well below the theoretical limit. Previous explanations were based on assuming a constant depth of the junction below the surface. In this work, preferred phosphorous diffusion at special line defects in grain boundaries is shown to lead to spikes in the p-n junctions even below flat surfaces. The curvature radii of the spherical p-n junction bending are measured by electron beam-induced current to be in the range of 300-500nm, leading to the observed type III avalanche breakdown voltages

Public access to research data in language documentation: Challenges and possible strategies

The Open Access Movement promotes free and unfettered access to research publications and, increasingly, to the primary data which underly those publications. As the field of documentary linguistics seeks to record and preserve culturally and linguistically relevant materials, the question of how openly accessible these materials should be becomes increasingly important. This paper aims to guide researchers and other stakeholders in finding an appropriate balance between accessibility and confidentiality of data, addressing community questions and legal, institutional, and intellectual issues that pose challenges to accessible data