Subquadratic J-V dependence and double injection in GaP

A new model for double injection in semiconductors containing deep traps is proposed whereby analytical prebreakdown J-V characteristics are obtained. The subquadratic behavior of J vs V is explained by the superposition of ohmic and nonohmic terms, their relative weights being related to the distance between the injecting contacts. The theory has been applied to the case of a GaP metal-n-n⁺ structure, giving a good fit of the experimental data.     

Spectral changes in El of Au-GaP diodes and negative resistance

Spectral changes in Au-GaP diodes at 77°K are observed when approaching the negative resistance region in forward bias. Both optical and transport behaviors are accounted for in terms of saturation of Si deep-acceptor recombination centers. An analytical model is proposed.     

Detecting small lung tumors in mouse models by refractive-index microradiology

Refractive-index (phase-contrast) radiology was able to detect lung tumors less than 1 mm in live mice. Significant micromorphology differences were observed in the microradiographs between normal, inflamed, and lung cancer tissues. This was made possible by the high phase contrast and by the fast image taking that reduces the motion blur. The detection of cancer and inflammation areas by phase contrast microradiology and microtomography was validated by bioluminescence and histopathological analysis. The smallest tumor detected is less than 1 mm(3) with accuracy better than 1 × 10(-3) mm(3). This level of performance is currently suitable for animal studies, while further developments are required for clinical application.     

Fabrication of single crystal CuGaS2 nanorods by X-ray irradiation

CuGaS(2) nanorods were synthesized by irradiating the precursor solution with intense X-rays. The products are single crystal nanorods with preferential [220] growth and a uniform size distribution. We also report on the photoresponse of drop-cast films of these nanorods.     

GaP:N photoluminescence at high nitrogen concentrations

The increase of nitrogen concentration considerably affects the 1.6°K photoluminescence spectra of very heavily doped GaP:N. The first moment of the spectral emission shifts towards the red, while the ratio of the intensities of large-momentum phonon replicas of A, NN₃ and NN₁ lines to the no-phonon lines increases. An explanation is proposed in terms of overlapping of the bound exciton wave functions.     

Valence band photoemission spectroscopy of a ternary layered semiconductor: ZnIn2S4

UV photoemission spectroscopy (UPS) experiments have been carried out on the layer compound ZnIn₂S₄ employing several different photon energies in the range $\text{h}\text{?}{}_{\mathrm{\omega }}\text{= 9.5?21.2}\text{eV}$. The energy distribution curves (EDC's) exhibit four valence band density of states structures besides the Zn 3d peak. These five peaks appear 0.90 eV, 1.6 eV, 4.3 eV, 5.8 eV and 8.7 eV respectively below the top of the valence band, E_v. The atomic orbital character of the shallowest peak A appears different from that of the three deeper valence band peaks B, C and D and this is discussed in terms of the more or less pronounced ionic character of the intralayer chemical bonds. These results demonstrate that an overall understanding of the electronic states in complex structures can be achieved by an approach based on photoemission experiments and chemical bonding considerations which has been widely used in the past to study simple binary layer compounds.