GaSbBi alloys and heterostructures: fabrication and properties

International audienceDilute bismuth (Bi) III-V alloys have recently attracted great attention, due to their properties of band-gap reduction and spin-orbit splitting. The incorporation of Bi into antimonide based III-V semiconductors is very attractive for the development of new optoelectronic devices working in the mid-infrared range (2-5 µm). However, due to its large size, Bi does not readily incorporate into III-V alloys and the epitaxy of III-V dilute bismides is thus very challenging. This book chapter presents the most recent developments in the epitaxy and characterization of GaSbBi alloys and heterostructures

Evaluation de l'effet d'un cache pare-soleil sur les mesures pyranométriques de rayonnement solaire duffus

Lors de la mesure de rayonnement solaire diffus à l’aide d’un pyranomètre muni d’un cache pare-soleil, celui-ci masque non seulement le disque solaire, mais encore une partie du ciel. On se propose d’évaluer la quantité de rayonnement ainsi perdue, dans le cas d’un ciel clair, d’un ciel intermédiaire et d’un ciel couvert pour un disque circulaire ainsi que pour un anneau pare-soleil.Tijdens de meting van de diffuse zonnestraling, maskeert deze niet alleen de zon maar ook een gedeelte van de hemel. We stellen voor de hoeveelheid van de aldus verloren straling te evalueren bij een heldere, een intermediaire en een betrokken hemel met een cirkelvormige en een bandvormige afschermer.When measuring solar diffuse radiation with a pyranometer equipped with a shading device, this one not only occults the solar disk but also a part of the sky. One evaluates the radiation lost, for clear, intermediate and overcast skies, when using a shading disk or ring

"Total solar irradiance observations from DIARAD/VIRGO"

The Differential Absolute Radiometer is making measurements of the total solar irradiance as part of the Variability of Irradiance and Gravity Oscillations experiment on the Solar and Heliospheric Observatory. We present the measurements made during its 7.8 years of operation, from 1996 until the present (2003). The aging due to UV exposure of the continuously measuring left channel is determined by comparison with the backup right channel; the loss in sensitivity of the left channel is 0.5 W/m2 or 364 ppm over 7.8 years. A raise of the total solar irradiance from a level of 1365.5 W/m2 at the end of the solar minimum in 1996 towards a maximum level of 1368 W/m2 at the beginning of 2002 has been measured by DIARAD

"Absolute accuracy and repeatability of the RMIB radiometers for TSI measurements"

Radiometers for the measurement of the total solar irradiance from space have been developed by D. Crommelynck at the Royal Meteorological Institute of Belgium (RMIB) since 1970. These radiometers, also used in the set of instruments defining the “World Radiometric Reference”, have successively flown on SPACELAB 1, ATLAS 1, EURECA, ATLAS 2, ATLAS 3, SOHO and HITCHHIKER, among them the SOLCON radiometer on the last STS107 flight. Other radiometers are under construction or integration for the upcoming missions: one as part of the SOVIM experiment on the International Space Station and SOVAP on the PICARD micro satellite. These radiometers have a symmetrical side by side cavity design. They are operated using the differential active cavity radiometric principle. In order to construct a long time series and to detect any variation between two cycles, it is important to know all the instrument parameters and make a clear distinction between what will lead to uncertainty on an absolute level and what guarantees the repeatability of the measurements. The purpose of this paper is to review these parameters; after a description of its principle, the instrumental equation will be established. The electrical parameters and the determination of remaining instrumental parameters are done during the characterisation phase at the RMIB. The results from the DIARAD/VIRGO radiometer on SOHO are presented. The repeatability of the measurements is found to be of the order of 100 ppm after correction of the in-flight aging. The accuracy on an absolute level is about 1.06 W m−2 for DIARAD left cavity. This accuracy is limited by the characterisation accuracy with a dominant role of the precision aperture area determination. The understanding of the behaviour of the DIARAD type instrument allows improving the design of the new radiometers on the upcoming missions

"Measurement and uncertainty of the long term total solar irradiance trend"

A possible long-term trend of the total solar irradiance could be a natural cause for climate variations on Earth. Measurement of the total solar irradiance with space radiometers started in 1978. We present a new total solar irradiance composite, with an uncertainty of ± 0.35 W m−2. From the minimum in 1995 to the maximum in 2002 the total solar irradiance increased by 1.6 W m−2. In between the minima of 1987 and 1995 the total solar irradiance increased by 0.15 W m−2

Measurement and Uncertainty of the Long-Term Total Solar Irradiance

A possible long term trend of the total solar irradiance could be a natural cause for climate variations on Earth. Measurement of the total solar irradiance with space radiometers have started in 1978. We present a new total solar irradiance composite, with an uncertainty of +/- 0.35 W/m2. From the minimum in 1995 to the maximum in 2002 the total solar irradiance increased by 1.6 W/m2. In between the minima of 1987 and 1995 the total solar irradiance increased by 0.15 W/m2