A two-colour heterojunction unipolar nanowire light-emitting diode by tunnel injection

We present a systematic study of the current-voltage characteristics and electroluminescence of gallium nitride (GaN) nanowire on silicon (Si) substrate heterostructures where both semiconductors are n-type. A novel feature of this device is that by reversing the polarity of the applied voltage the luminescence can be selectively obtained from either the nanowire or the substrate. For one polarity of the applied voltage, ultraviolet (and visible) light is generated in the GaN nanowire, while for the opposite polarity infrared light is emitted from the Si substrate. We propose a model, which explains the key features of the data, based on electron tunnelling from the valence band of one semiconductor into the conduction band of the other semiconductor. For example, for one polarity of the applied voltage, given a sufficient potential energy difference between the two semiconductors, electrons can tunnel from the valence band of GaN into the Si conduction band. This process results in the creation of holes in GaN, which can recombine with conduction band electrons generating GaN band-to-band luminescence. A similar process applies under the opposite polarity for Si light emission. This device structure affords an additional experimental handle to the study of electroluminescence in single nanowires and, furthermore, could be used as a novel approach to two-colour light-emitting devices.Comment: 9 pages, 11 figure

Respiratory Care Protocols in Neonatal Intensive Care

Neonatal respiratory care involves physicians with variable backgrounds treating multiple respiratory problems and populations with a number of invasive and non-invasive devices and strategies. Unfortunately, there is a lack of strong evidence to guide the most adequate management for several specific situations. Altogether, this complexity leads to significant practice variability that can affect patient and health care outcomes. Respiratory care protocols, guided by evidence and/or consensus, are an attractive solution to promote standardization of care and reduction of unnecessary practice variations. Indeed, despite the limited evidence supporting the use of respiratory protocols in neonates, a significant number of units have already developed and implemented them into clinical practice. Respiratory care protocols appear to promote evidence-based practices, discourage outdated approaches and ultimately improve patient safety