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The detector performance and presence of Te secondary-phase defects distribution were investigated in CdMnTe (CMT) crystals prepared with different cooling rates. Detectors fabricated from fast-cooled CMT crystals exhibit a relatively poor detector performance, although IR transmission microscopy measurements show that the Te secondary-phase defects have a lower concentration and smaller size compared to slow-cooled crystals. Current deep-level transient spectroscopy (I-DLTS) measurements for both CMT detectors reveal the same trap levels, but there is a clear difference in the densities for the 0.26- and 0.42-eV traps for the two different cooling schemes. These two traps are probably attributed to Cd vacancies and Te anti-site defects, respectively. In addition, there is some likelihood that the traps are anti-correlated with respect to each other. [ABSTRACT FROM AUTHOR]

We investigated the photoluminescence (PL) of CdTe doped with indium using above- and below-bandgap excitation at temperatures of 4.5-20 K. We recorded and measured the selectively excited PL arising from the recombination of donor-acceptor (D-A) pairs with the A-center acceptor in the spectral region of the 1.4-eV PL band for different excitation photon energies, hωEXC. Sharp, strong PL lines that shifted with hωEXC over the total contour of the D-A pair band represented the selective pair luminescence (SPL). The energy difference of ∼125 meV between the excited- and ground-state of the charged D-A pair is very close to the 6-longitudinal-optical phonon energy in CdTe. This multiplicity favors the relaxation of an excited hole to the ground state of an acceptor, and increases the probability of recombination in the D-A pair. The SPL line quenches with temperature, characteristically with energy of 6-14 meV for D-A pairs with different D-A distances. The temperature shift of the 1.4-eV band supposedly is caused by the redistribution of occupied- and empty-shallow donors neighboring the A-center. [ABSTRACT FROM AUTHOR]

Using photoluminescence (PL) and current deep-level transient spectroscopy (I-DLTS), we investigated the electronic defects of indium-doped detector-grade CdMnTe:In (CMT:In) crystals grown by the vertical Bridgman method. We similarly analyzed CdZnTe:In (CZT:In) and undoped CdMnTe (CMT) crystals grown under the amount of same level of excess Te and/or indium doping level to detail the fundamental properties of the electronic defect structure more readily. Extended defects, existing in all the samples, were revealed by synchrotron white beam x-ray diffraction topography and scanning electron microscopy. The electronic structure of CMT is very similar to that of CZT, with shallow traps, A-centers, Cd vacancies, deep levels, and Te antisites. The 1.1-eV deep level, revealed by PL in earlier studies of CZT and CdTe, were attributed to dislocation-induced defects. In our I-DLTS measurements, the 1.1-eV traps showed different activation energies with applied bias voltage and an exponential dependence on the trap-filling time, which are typical characteristics of dislocation-induced defects. We propose a new defect-trap model for indium-doped CMT crystals. [ABSTRACT FROM AUTHOR]

CdZnTe crystals often exhibit nonuniformities due to the presence of Te inclusions and dislocations. High concentrations of such defects in these crystals generally entail severe charge-trapping, a major problem in ensuring the device's satisfactory performance. In this study, we employed a high-intensity, high-spatial-resolution synchrotron x-ray beam as the ideal tool to generate charges by focusing it over the large Te inclusions, and then observing the carrier's response at room- and at low-temperatures. A high spatial 5-μm resolution raster scan revealed the fine details of the presence of extended defects, like Te inclusions and dislocations in the CdZnTe crystals. A noticeable change was observed in the efficiency of electron charge collection at low temperature (1 °C), but it was hardly altered at room-temperature. [ABSTRACT FROM AUTHOR]

By analyzing photoconductive decay curves, we compared the surface recombination velocities of semi-insulating CdMnTe:In crystals grown by the vertical Bridgman method with or without surface passivation. Sulfur passivation effectively prevents the formation of a conductive Te oxide layer on the CdMnTe surface and reduces the surface recombination velocities by about one third. We demonstrated, from IR observations of the distribution maps of Te precipitates, that their configuration affects the anomalous photoconductive decay curves and the gamma-ray spectrum in some areas of the CdMnTe crystal. Notably, not only the size but also the spatial configuration of the Te precipitates modulates the carrier-transport properties. [ABSTRACT FROM AUTHOR]

The focus of this paper is to evaluate thick, 20×20×10 and 10×10×10 mm3, cadmium zinc telluride (CZT), Cd0.9Zn0.1Te, crystals grown using the traveling heater method (THM). The phenomenal spectral performance and small size and low concentration of Te inclusions/precipitates of these crystals indicate that the THM is suitable for the mass production of CZT radiation detectors that can be used in a variety of applications. Our result also proves that with careful material selection using IR and high-quality fabrication processes, the theoretical energy resolution limit can be achieved. [ABSTRACT FROM AUTHOR]

The surface recombination velocity of a Cd[sub 1-χ]Zn[sub χ]Te (CZT) radiation detector treated by mechanical polishing and by a standard 5% bromine in methanol chemical etch is reported. The light power dependence of the surface recombination velocity was measured using dc photoconductivity. The results reveal that the surface recombination velocity is a function of the electron generation rate, which can be described by a Shockley-Read one-center model. It was observed that the surface recombination velocity of the CZT detector treated by polishing only is much larger than that treated with polishing followed by chemical etching. The correlation of dc photoconductivity and low-temperature photoluminescence measurements of the CZT detector is also discussed. [ABSTRACT FROM AUTHOR]

In this article, we report on the charge-transport characteristics of a new quaternary material Cd1-xZnxTe1-ySey (CZTS) grown by the Traveling Heater Method (THM). The as-grown CZTS material was found to possess fewer Te inclusions than CZT†. Moreover, high resistivity of ∼1-2x1010 ohm-cm was achieved, meeting the requirements of most gamma-ray detector applications. The mobility-lifetime product for electrons [(μτ)e] was measured to be ∼4x10-3 cm2/V. The energy resolution for the quasi-hemispherical detector fabricated from the as-grown CZTS ingot obtained was ∼2.8% (FWHM) at 662 keV. [ABSTRACT FROM AUTHOR]

Presents a study that investigated carbon dioxide laser processing of diffusion-induced lattice imperfections in silicon. Background on the effect of the high-temperature diffusion of phosphorous into crystalline silicon; Analysis of the advantages of depositing the pulse energy through free-carrier transitions; Assessment of the transmission electron microscopy results.

Presents a study which measured the absorption coefficient of carbon dioxide laser radiation in moderately-doped gallium-arsenide:zinc crystals as a function of the intensity of the laser pulses. Difficulty in the use of lasers to process gallium-arsenic material; Experimental details; Results and discussion; Conclusions.

Investigates the time-resolved optical reflectivity of ion-implanted silicon during carbon dioxide laser irradiation. Details on the experiment; Results; Conclusions.

Focuses on a study which characterized iodide crystals with semitransparent metal overlayers of indium and tin using low-temperature photoluminescence spectroscopy. Discussion of the interaction between mercuric iodide and semitransparent metal overlayers; Application of photoluminescence spectroscopy; Observation on the behavior of photodetectors and indium-tin-oxide.

Deals with a study of mercuric-iodide photodetectors with sputtered indium-tin-oxide entrance electrodes using low-temperature photoluminescence spectroscopy. Experimental details; Results and discussion; Conclusion.

Presents information on a study which demonstrated the shallow melting of thin heavily doped silicon layers by pulsed carbon dioxide laser irradiation.

Presents a study that measured the melting of silicon surfaces by high-power pulsed microwave radiation. Experimental details on the microwave source; Experimental results and discussion; Information on the microwave-induced particle emissions and fluorescence.

Presents information on a study which characterized the low-temperature photoluminescence spectra of several mercuric iodide detectors and off-stoichiometric bulk material. Experimental method; Raman measurements; Description of the photoluminescence spectra; Examination of the near-band-gap photoluminescence.

Focuses on a study which measured low-temperature photoluminescence spectra of detector grade direct-band-gap ternary compound to obtained information about shallow level defect concentration during mechanical polishing and chemical etching processes. Information on the ternary compound; Methodology of the study; Results and discussion.

Presents a study which introduced extrinsic defects into mercuric iodide during processing using low temperature photoluminescence spectroscopy measurements. Experimental technique; Results of the study; Conclusion.

Investigates the semitransparent palladium contacts on mercuric iodide. Use of the photoluminescence spectroscopy process; Modifications in the stoichiometry within the palladium/mercuric iodide interfacial region; Significance of dominant traps in the application of nuclear detection.

Presents a study which investigated the near-band-gap 4.2 K photoluminescence spectrum of undoped mercuric iodide in its red tetragonal form. Experimental techniques used; Results and discussion.

Presents information on a study which examined the effects of chemical etching, heating, and vacuum exposure on the defect structure of mercuric iodide crystals. Methods; Results; Discussion.

Models that place design constraints on devices which are used to measure the leakage currents in high-resistivity semiconductor materials are presented. If these design constraints are met, these models can then be used to quantitatively predict the surface sheet resistance of devices which are dominated by surface leakage currents. As a result, a means is provided to directly compare passivation techniques which are developed to decrease surface leakage currents. Furthermore, these models illustrate the necessity for inclusion of relevant geometrical data on sample size and shape and electrode configuration when reporting results of surface passivation techniques. These models specifically examine the case where a dc potential is applied across two electrodes on the surface of a semiconductor substrate which has a surface layer with lower resistivity than the bulk material. We describe several of the more common configurations used in analyzing passivation techniques for compounds of [Cd.sub.1-x][Zn.sub.x]Te (CZT) used for room-temperature radiation detection. Index Terms--Cadmium zinc telluride, electrostatic field modeling, leakage current, surface passivation.