Acknowledgements This document has been produced primarily by a joint EURACHEM/CITAC Working Group with the composition shown (right). The editors are grateful to all these individuals and organisations and to others who have contributed comments, advice and assistance.
We have fabricated doubly clamped beams from GaAs/AlGaAs quantum-well heterostructures containing a high-mobility two-dimensional electron gas ͑2DEG͒. Applying an rf drive to in-plane side gates excites the beam's mechanical resonance through a dipole–dipole mechanism. Sensitive high-frequency displacement transduction is achieved by measuring the ac emf… (More)
Acknowledgements This document has been produced primarily by a joint Eurachem/CITAC Working Group with the composition shown (right). The editors are grateful to all these individuals and organisations and to others who have contributed comments, advice and assistance. Preface Measurement underpins a wide range of socioeconomic activities, both domestic… (More)
We present magnetotransport measurements on freely suspended two-dimensional electron gases from Al x Ga 1Ϫx As/GaAs heterostructures. The technique to realize such devices relies on a specially molecular beam epitaxy grown GaAs/Al x Ga 1Ϫx As-heterostructure, including a sacrificial layer. We fabricated simple mini-Hall-bars as well as quantum cavities and… (More)
We report on magnetotransport measurements in two MBE-grown GaAs/AlGaAs superlattices formed by wide and narrow quantum wells and thin Si-doped barriers subject to tilted magnetic fields. It has been shown that illumination of the strongly coupled superlattice with narrow wells leads to reduction of its dimensionality from the 3D to 2D. The… (More)
The dead time of the detection system of a quadrupole ICP-MS is estimated and the different calculation methods are rated for transparency and ease of use. They are optimised to yield minimum uncertainty of measurement and minimum bias. The dead time is calculated only from the count rates of the two isotopes and the precision of the count rates is governed… (More)