Photoluminescence evaluation of pseudomorphic high electron mobility transistor device waters

Photoluminescence (PL) has been used for some time the evaluation of pseudomorphic high electron mobility transistor material structures. Among the results routinely obtained from these structures are estimates of electron sheet density in the InGaAs channel, either from empirical relationships or from first principles (from direct observation of the Fermi level). We present a semiempirical line shape model for the study of PL line shapes at low temperatures. We show that the primary source of error for optical measurement of the sheet density is in the filling of the channel by electrons injected by the incident laser. We also demonstrate the potential for extraction of structural parameters such as channel composition and thickness from careful observation of variations in PL transition energies.     

Inclusiveπ° production in 360 GeVpp interactions using the european hybrid spectrometer

The intermediate and forward gamma detectors of EHS are used to reconstructπ°'s produced by 360 GeV/cpp interactions in the Rapid Cycling Bubble Chamber (RCBC). Using thepp forwardbackward symmetry, the inclusiveπ° production cross section is obtainedσ _π°=(132±11) mb. The averageπ° multiplicity is determined as a function of the charged particle multiplicity. The (1?x) dependence is given for differentp _T regions.     

Optical repeater using PFM at 1 GHz

We report the first realization of PFM optical communication with a repeater station, using double heterostructure GaAs/GaAlAs semiconductor lasers. The system uses the property of semiconductor lasers for which the optical pulse rate can be locked by an external modulation of the injection current in the vicinity of the resonance frequency of the laser. This modulation scheme has the advantages of a high information rate capability by using the "spiking" resonance of the laser and, more importantly, of a simple repeater station in which another pulsing laser acts as a regenerative pulse amplifier.     

Products of graceful trees

We give some conditions on H and $\text{G}$ for the rooted product H($\text{G}$) to be graceful. These conditions extend and unify previous results.     

An electron spectroscopic investigation of the interaction of methanol with polycrystalline aluminum

X-ray and ultraviolet photoelectron spectroscopic results are reported for the interaction of CH₃OH with clean polycrystalline Al in the temperature range 110–500 K. Methanol is moleculary chemisorbed at low exposure and low temperature (110 K) followed by condensation at higher exposure. Bonding mechanisms and geometries in the condensed and chemisorbed layers are discussed. The multilayers desorb beginning near 170 K and the chemisorbed layer is converted into a surface methoxide. Room temperature adsorption also leads to formation of the methoxide species which is stable to ～500 K, at which point it decomposes evolving CH₄ and leaves the surface oxidized.