Enhancement of Mercuric Iodide Detector Performance Through Crystal Growth in Microgravity: the Roles of Lattice Order

1997 ◽  
Vol 487 ◽  
Author(s):  
Bruce Steiner ◽  
Lodewijk Van Den Berg ◽  
Uri Laor
Keyword(s):  
Crystal Growth ◽  
Crystal Lattice ◽  
Hole Mobility ◽  
Radiation Detectors ◽  
High Energy ◽  
Structural Features ◽  
Mercuric Iodide ◽  
Detector Performance ◽  
Lattice Order ◽  
Extraneous Material

AbstractThe hole-mobility•carrier-lifetime product of α mercuric iodide high energy radiation detectors has been enhanced through vapor crystal growth in microgravity. This improvement is closely correlated with specific characteristics of the crystal lattice, which have been identified by high resolution synchrotron x-ray diffraction imaging. These structural features and the associated performance are now being approached in terrestrial growth of α mercuric iodide.Gravity may affect the uniformity of this crystal lattice in two distinct ways: 1) directly through deformation that it imposes on the lattice during growth and 2) indirectly through convection, which mixes any extraneous material. Inclusions associated with these processes harden the lattice and facilitate lattice folding. These changes affect the electronic parameters of detectors made from the crystals. As purification procedures are optimized, the incorporation of extraneous material is curtailed, enhancing electronic properties in spite of lattice flexing through loss of precipitation hardening.These studies provide insight into the contribution of various aspects of crystalline order in α-mercuric iodide crystals to property improvement. This knowledge has led to modification of requirements for starting materials, adjustment of physical vapor growth procedures, and change in crystal handling procedures. As a result, the electronic performance of terrestrially grown radiation detectors has been improved, and we provide evidence that further enhancement is still possible.

Crystal Growth and Characterization of CdTe and Cd0.9Zn0.1Te for Nuclear Radiation Detectors

2007 ◽  
Vol 1038 ◽  
Author(s):  
Krishna Mandal ◽  
Sung H. Kang ◽  
Michael Choi ◽  
Alket Mertiri ◽  
Gary W Pabst ◽  
...  
Keyword(s):  
Hole Mobility ◽  
Inclusion Size ◽  
Radiation Detectors ◽  
High Energy ◽  
Nuclear Radiation ◽  
Detector Performance ◽  
Current Voltage ◽  
Ir Transmission ◽  
Vertical Bridgman ◽  
Nuclear Radiation Detectors

AbstractCdTe and Cd0.9Zn0.1Te (CZT) crystals have been studied extensively at EIC Laboratories, Inc. for various applications including x- and γ-ray imaging and high energy radiation detectors. The crystals were grown from in-house zone refined ultra pure precursor materials using a vertical Bridgman furnace. The growth process has been monitored, controlled and optimized by a computer simulation and modeling program (MASTRAPP). The grown crystals were thoroughly characterized after sequential surface passivations and post-growth annealing treatments with and without component overpressures. The infrared (IR) transmission images of the post-treated CdTe and CZT crystals showed average Te inclusion size of ∼10 μm for CdTe crystal and ∼8 μm for CZT crystal. The etch pit density was ≤ 5×104 cm−2 for CdTe and ≤ 3×104 cm−2 for CZT. Various planar and Frisch collar detectors were fabricated and evaluated. From the current-voltage measurements, the electrical resistivity was estimated to be ∼1.5×1010 Ω·cm for CdTe and 2-5×1011 Ω·cm for CZT. The Hecht analysis of electron and hole mobility-lifetime products (μτe and μτh) showed μτe=2×10−3 cm2/V (μτh=8×10−5 cm2/V) and μτ3-6×10−3 cm2/V (μτh=4-6×10−5 cm2/V) for CdTe and CZT, respectively. Final assessments of the detector performance have been carried out using 241Am (60 keV) and 137Cs (662 keV) energy sources and the results are presented in this paper.

Investigation of Lead Iodide Crystals for Use as High Energy Solid State Radiation Detectors

1993 ◽  
Vol 302 ◽  
Author(s):  
Dominique C. David ◽  
R. B. James ◽  
H. Feemster ◽  
R. Anderson ◽  
A. J. Antolak ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Solid State ◽  
Gamma Rays ◽  
Room Temperature ◽  
Radiation Detectors ◽  
High Energy ◽  
Device Performance ◽  
Lead Iodide ◽  
State Radiation ◽  
Energy Gamma

ABSTRACTSignificant developments have occurred in the technology of room-temperature PbI2 nuclear sensors which lead to some improvements in the detection of high energy gamma-rays. Discussion of crystal growth, purification, monitoring purification, and detector processing are reviewed as they relate to device performance.

Computational Models for Crystal Growth of Radiation Detector Materials: Growth of CZT by the EDG Method

2007 ◽  
Vol 1038 ◽  
Author(s):  
Jeffrey J. Derby ◽  
David Gasperino
Keyword(s):  
Crystal Growth ◽  
Computational Models ◽  
Radiation Detector ◽  
Radiation Detection ◽  
Radiation Detectors ◽  
Growth Conditions ◽  
Detector Performance ◽  
Detection Systems ◽  
Crystal Properties ◽  
Detector Materials

AbstractCrystals are the central materials element of most gamma radiation detection systems, yet there remains surprisingly little fundamental understanding about how these crystals grow, how growth conditions affect crystal properties, and, ultimately, how detector performance is affected. Without this understanding, the prospect for significant materials improvement, i.e., growing larger crystals with superior quality and at a lower cost, remains a difficult and expensive exercise involving exhaustive trial-and-error experimentation in the laboratory. Thus, the overall goal of this research is to develop and apply computational modeling to better understand the processes used to grow bulk crystals employed in radiation detectors. Specifically, the work discussed here aims at understanding the growth of cadmium zinc telluride (CZT), a material of long interest to the detector community. We consider the growth of CZT via gradient freeze processes in electrodynamic multizone furnaces and show how crucible mounting and design are predicted to affect conditions for crystal growth.

State-of-the-art of crystal growth and nuclear spectroscopic evaluation of mercuric iodide radiation detectors

1978 ◽  
Vol 150 (1) ◽  
pp. 71-77 ◽  
Author(s):  
M. Schieber ◽  
I. Beinglass ◽  
G. Dishon ◽  
A. Holzer ◽  
G. Yaron
Keyword(s):  
Crystal Growth ◽  
State Of The Art ◽  
Radiation Detectors ◽  
Mercuric Iodide

scholarly journals Hall Study of Conductive Channels Formed in Germanium by Beams of High-Energy Light Ions

2021 ◽  
Vol 66 (1) ◽  
pp. 62
Author(s):  
S.V. Lysochenko ◽  
Yu.S. Zharkikh ◽  
O.G. Kukharenko ◽  
O.V. Tretiak ◽  
M.G. Tolmachov
Keyword(s):  
Crystal Lattice ◽  
Hall Mobility ◽  
Hole Mobility ◽  
High Energy ◽  
Implantation Dose ◽  
Structure Defects ◽  
Light Ions ◽  
High Energy Ions ◽  
Microelectronics Technology ◽  
High Energy Particles

The implantation of the high-energy ions of H+ or He+ in germanium leads to the creation of buried conductive channels in its bulk with equal concentrations of acceptor centers. These centers are the structure defects of the crystal lattice which arise in the course of deceleration of high-energy particles. This method of introducing electrically active defects is similar to the doping of semiconductors by acceptor-type impurities. It has been established that the density of defects increases with the implantation dose till ≈5×10^15 cm−2. The further increase of the implantation dose does not affect the level of doping. In the range of applied doses (10^12–6×10^16) cm−2, the Hall mobility of holes in the formed conducting channels is practically independent of the implanted dose and is about (2-3)×10^4 cm2/Vs at 77 K. The doping ofthe germanium by high-energy ions of H+ or He+ to obtain conducting regions with high hole mobility can be used in the microelectronics technology.

Keys to the Enhanced Performance of Mercuric Iodide Radiation Detectors Provided by Diffraction Imaging

1999 ◽  
Vol 590 ◽  
Author(s):  
Bruce Steiner ◽  
Lodewijk van den Berg ◽  
Uri Laor
Keyword(s):  
High Resolution ◽  
Electronic Transport ◽  
Structural Control ◽  
Room Temperature ◽  
Radiation Detectors ◽  
High Energy ◽  
Space Program ◽  
Mercuric Iodide ◽  
High Energy Radiation ◽  
Diffraction Imaging

ABSTRACTHigh resolution monochomatic diffraction imaging is playing a central role in the optimization of novel high energy radiation detectors for superior energy resolution at room temperature. In the early days of the space program, the electronic transport properties of mercuric iodide crystals grown in microgravity provided irrefutable evidence that substantial property improvement was possible. Through diffraction imaging, this superiority has been traced to the absence of inclusions. At the same time, other types of irregularity have been shown to be surprisingly less influential. As a result of the knowledge gained from these observations, the uniformity of terrestrial crystals has been modified, and their electronic properties have been enhanced. Progress toward property optimization through structural control is described.

High-purity Ge x-ray detectors: Sensitivity factors and usefulness

1990 ◽  
Vol 48 (2) ◽  
pp. 548-548
Author(s):  
E. B. Steel
Keyword(s):  
High Purity ◽  
High Energy ◽  
Quantitative Chemical Analysis ◽  
Detector Performance ◽  
X Ray ◽  
Detector Sensitivity ◽  
Specimen Holder ◽  
Many Instruments ◽  
Charge Resolution ◽  
Sensitivity Factors

High Purity Germanium (HPGe) x-ray detectors are now commercially available for the analytical electron microscope (AEM). The detectors have superior efficiency at high x-ray energies and superior resolution compared to traditional lithium-drifted silicon [Si(Li)] detectors. However, just as for the Si(Li), the use of the HPGe detectors requires the determination of sensitivity factors for the quantitative chemical analysis of specimens in the AEM. Detector performance, including incomplete charge, resolution, and durability has been compared to a first generation detector. Sensitivity factors for many elements with atomic numbers 10 through 92 have been determined at 100, 200, and 300 keV. This data is compared to Si(Li) detector sensitivity factors.The overall sensitivity and utility of high energy K-lines are reviewed and discussed. Many instruments have one or more high energy K-line backgrounds that will affect specific analytes. One detector-instrument-specimen holder combination had a consistent Pb K-line background while another had a W K-line background.

Correlation Between the V-I Characteristics of (0001) 4H-SiC PN Junctions Having Different Structural Features and Synchrotron X-ray Topography

2008 ◽  
Vol 1069 ◽  
Author(s):  
Ryoji Kosugi ◽  
Toyokazu Sakata ◽  
Yuuki Sakuma ◽  
Tsutomu Yatsuo ◽  
Hirofumi Matsuhata ◽  
...  
Keyword(s):  
High Energy ◽  
Structural Features ◽  
Incidence Geometry ◽  
Voltage Source ◽  
Large Area ◽  
Chip Area ◽  
Power Mosfets ◽  
X Ray ◽  
Pn Junctions ◽  
The Difference

ABSTRACTIn practical use of the SiC power MOSFETs, further reduction of the channel resistance, high stability under harsh environments, and also, high product yield of large area devices are indispensable. Pn diodes with large chip area have been already reported with high fabrication yield, however, there is few reports in terms of the power MOSFETs. To clarify the difference between the simple pn diodes and power MOSFETs, we have fabricated four pn-type junction TEGs having the different structural features. Those pn junctions are close to the similar structure of DIMOS (Double-implanted MOS) step-by-step from the simple pn diodes. We have surveyed the V-I characteristics dependence on each structural features over the 2inch wafer. Before their fabrication, we formed grid patterns with numbering over the 2inch wafer, then performed the synchrotron x-ray topography observation. This enables the direct comparison the electrical and spectrographic characteristics of each pn junctions with the fingerprints of defects.Four structural features from TypeA to TypeD are as follows. TypeA is the most simple structure as same as the standard pn diodes formed by Al+ ion implantation (I/I), except that the Al+ I/I condition conforms to that of the p-well I/I in the DIMOS. The JTE structure was used for the edge termination on all junctions. While the TypeA consists of one p-type region, TypeB and TypeC consists of a lot of p-wells. The difference of Type B and C is a difference of the oxide between the adjacent p-wells. The oxide of TypeB consists of the thick field oxide, while that of TypeC consists of the thermal oxide corresponding to the gate oxide in the DIMOS. In the TypeD structure, n+ region corresponding to the source in the DIMOS was added by the P+ I/I. The TypeD is the same structure of the DIMOS, except that the gate and source contacts are shorted. The V-I measurements of the pn junctions are performed using the KEITHLEY 237 voltage source meters with semi-auto probe machine. An active area of the fabricated pn junctions TEGs are 150um2 and 1mm2. Concentration and thickness of the drift layer are 1e16cm−3 and 10um, respectively.In order to compare the V-I characteristics of fabricated pn junctions with their defects information that obtained from x-ray topography measurements directly, the grid patterns are formed before the fabrication. The grid patterns were formed over the 2inch wafer by the SiC etching. The synchrotron x-ray topography measurements are carried out at the Beam-Line 15C in Photon-Factory in High-Energy-Accelerator-Research-Organization. Three diffraction conditions, g=11-28, -1-128, and 1-108, are chosen in grazing-incidence geometry (improved Berg-Barrett method).In the presentation, the V-I characteristics mapping on the 2inch wafer for each pn junctions, and the comparison of V-I characteristics with x-ray topography will be reported.

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