Enhancement of mercuric iodide detector performance through increases in wafer uniformity by purification and crystal growth in microgravity

1999 ◽  
Vol 86 (8) ◽  
pp. 4677-4687 ◽  
Author(s):  
Bruce Steiner ◽  
Lodewijk van den Berg ◽  
Uri Laor
Keyword(s):  
Crystal Growth ◽  
Mercuric Iodide ◽  
Detector Performance

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.

Defects in Silver-Doped Mercuric Iodide Crystals and their Effect on X-Ray and Gamma-Ray Detector Performance

1993 ◽  
Vol 302 ◽  
Author(s):  
R. B. James ◽  
X. J. Bao ◽  
T. E. Schlesinger ◽  
A. Y. Cheng ◽  
V. M. Gerrish
Keyword(s):  
Gamma Ray ◽  
Electrical Contacts ◽  
Source Material ◽  
Broad Emission Band ◽  
Interfacial Region ◽  
Mercuric Iodide ◽  
Detector Performance ◽  
X Ray ◽  
Silver Silver ◽  
Gamma Ray Detector

ABSTRACTThe processing steps associated with purification of source material, crystal growth, and attachment of electrical contacts can introduce defects into mercuric iodide (HgI2) that degrade the performance of detectors. We have employed low-temperature photoluminescence (PL) spectroscopy to study radiative recombination centers in the interfacial region between a thin semitransparent film of silver and mercuric iodide. The Ag film was found to introduce a new broad emission band centered at 5490 Å in the photoluminescence spectrum of HgI2. This PL feature can be used as a signature to identify the existence of Ag as a contaminant in HgI2 crystals and detectors. Experiments were also conducted on mercuric iodide surfaces that had been doped with silver, and the results showed that Ag is a rapid diffuser in bulk HgI2. Detectors with silver electrodes were also fabricated and tested using an americium-241 gamma-ray source. Large increases in the leakage currents were observed for the Ag-doped HgI2 devices, indicated that Ag impurities are electrically active in HgI2. These measurements show that silver is unacceptable as an electrode material for mercuric iodide x-ray and gamma-ray detector applications. In addition, they reveal that caution must be taken during handling of mercuric iodide source material, crystals, and detectors to avoid contact with silver, silver compounds, or with any material that contains silver as a contaminant.

scholarly journals Crystal growth and detector performance of large size High-purity Ge crystals

2015 ◽  
Vol 39 ◽  
pp. 54-60 ◽  
Author(s):  
Guojian Wang ◽  
Mark Amman ◽  
Hao Mei ◽  
Dongming Mei ◽  
Klaus Irmscher ◽  
...  
Keyword(s):  
Crystal Growth ◽  
High Purity ◽  
Detector Performance ◽  
Large Size

Modified purification of mercuric iodide for crystal growth

1988 ◽  
Vol 89 (1) ◽  
pp. 86-92 ◽  
Author(s):  
N.L. Skinner ◽  
C. Ortale ◽  
M.M. Schieber ◽  
L. Van Den Berg
Keyword(s):  
Crystal Growth ◽  
Mercuric Iodide

Polycrystalline mercuric iodide films: deposition, properties, and detector performance

2002 ◽  
Vol 49 (4) ◽  
pp. 1965-1967 ◽  
Author(s):  
U.N. Roy ◽  
Y. Cui ◽  
G. Wright ◽  
C. Barnett ◽  
A. Burger ◽  
...  
Keyword(s):  
Mercuric Iodide ◽  
Detector Performance

Gravitational Effects on Mercuric Iodide Crystal Growth

1998 ◽  
Vol 551 ◽  
Author(s):  
Bruce Steiner ◽  
Lodewijk Van Den Berg ◽  
Uri Laor
Keyword(s):  
Crystal Growth ◽  
Mercuric Iodide ◽  
Gravitational Effects ◽  
Vapor Growth ◽  
Turn On ◽  
Electronic Performance ◽  
Diffraction Imaging ◽  
Characterization Studies ◽  
And Performance ◽  
Iodide Crystal

AbstractGravity can affect the physical vapor growth of mercuric iodide in two distinct ways. First, gravity will induce convection during growth, which strongly mixes residual impurities and any elementary gases resulting from imperfect stoichiometry, either of which can then form precipitates in the growing crystal. Second, gravity loads the resulting crystal, which is particularly soft while still hot, especially in the absence of precipitates. We have investigated the effects of these processes on the resulting crystalline regularity and the effects of various types of irregularity, in turn, on performance.High resolution synchrotron x-radiation diffraction imaging of three generations of crystals, grown both in microgravity and in full gravity, provide graphic evidence of the influence of gravity on mercuric iodide crystal growth. These images tie together the results of other characterization studies, identifying the crystallographic sources of the observed property enhancement in microgravity. The first process, convection, is found to be particularly important, both in its influence on observed crystalline regularity and in the resulting electronic performance of detectors made from these crystals.As a result of these investigations, the crystalline regularity and performance of terrestrial crystals has been substantially improved, although the resulting crystals have not yet achieved parity with the performance of crystals grown in microgravity. We propose new experiments in microgravity for property optimization.

Sign in / Sign up

Export Citation Format

Share Document