Lead poisoning is a serious environmental concern, which is a health threat. Existing technologies al- ways have some drawbacks, which restrict their application ranges, such as real time monitoring. To solve this problem, glutathione was functionalized on the Au-coated gate area of the pseudomorphic high electron mobility transistor （pHEMT） to detect trace amounts of Pb^2＋. The positive charge of lead ions will cause a positive potential on the Au gate of the pHEMT sensor, which will increase the current between the source and the drain. The response range for Pb^2＋ detection has been determined in the concentrations from 0.1 pmol/L to 10 pmol/L. To our knowledge, this is currently the best result for detecting lead ions.
A1Sb/InAs quantum well （QW） structures and InAs films on GaAs （001） substrates were grown by molecular beam epitaxy （MBE）. We investigated the dependence of electron mobility and two-dimensional electron gas （2DEG） concen- tration on the thickness of an InAs Channel. It is found that electron mobility as high as 19050 cm2 · V-1 · s-1 has been achieved for an InAs channel of 22.5 nm. The Hall devices with high sensitivity and good temperature stability were fabricated based on the A1Sb/InAs QW structures. Their sensitivity is markedly superior to Hall devices of InAs films.
