A Contactless Method for Measuring the Lifetimes of Nonequilibrium Charge Carriers in Semiconductors

A setup for measuring the lifetimes of nonequilibrium charge carriers in semiconductors is described. Its performance characteristics are as follows: the range of lifetime measurements is from 50 ns to 200 s, the spatial resolution is 100 s, and the operation speed is 1000 measurements per second. Excess carriers are generated by short laser pulses. An increment of the carrier concentration is detected by a change in the microwave-power absorption. A vacuumless cryostat is of an original design and is simple and convenient in operation. A sample can be replaced in 1 min. The high metrological characteristics of the setup are ensured by using a computer for data recording, an electron time-to-code converter, and a rapid positioning device.     

Effect of grain boundaries on the properties of cadmium telluride grown under nonequilibrium conditions

Microphotoluminescence spectroscopy and imaging were used to study the effect of grain boundaries on the properties of textured CdTe polycrystals with a single-crystal grain size of 1–2 mm grown under nonequilibrium conditions. The technological procedure included low-temperature synthesis and purification of the material via congruent sublimation, with subsequent deposition under conditions of gas-dynamic vapor flow and high-rate low-temperature condensation. Microluminescence probing revealed that most of the grain boundaries are decorated with local centers emitting in the 1.4-eV band of donor-acceptor recombination involving shallow donors and A-center acceptors. The boundary regions are, to some extent, free of nonradiative recombination centers active at room temperature. Gettering activity of the grain boundaries could be detected at the distances up to 100 μm, which reflects the specific features of the nonequilibrium crystallization conditions of the material under study. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 37, No. 11, 2003, pp. 1298–1302. Original Russian Text Copyright ? 2003 by Ushakov, Klevkov.     

Multipoles of the SLS storage ring: manufacturing and magnetic measurements

The quadrupoles and sextupoles for the Swiss Light Source had severe requirements on the manufacturing tolerances and the alignment of their magnetic axis. The 306 multipoles were manufactured, and magnetically measured at BINP and after delivery also at PSI. The features of manufacturing and precise magnetic measurements of SLS multipoles are discussed.