Optimal width of barrier region in X/{gamma}-ray Schottky diode detectors based on CdTe and CdZnTe

Journal Article · Thu Feb 07 04:00:00 EST 2013 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4790358· OSTI ID:22102262

Kosyachenko, L. A.; Melnychuk, S. V.; Sklyarchuk, V. M.; Maslyanchuk, O. L.; Sklyarchuk, O. V. ^[1]; Aoki, T. ^[2]; Lambropoulos, C. P. ^[3]; Gnatyuk, V. A. ^[4]; Grushko, E. V. ^[1]

---

1. Chernivtsi National University, 58012 Chernivtsi (Ukraine)
2. Research Institute of Electronics, Shizuoka University, Johoku, Hamamatsu 432-8011 (Japan)
3. Technological Educational Institute of Chalkida, Psahna, Evia GR 34400 (Greece)
4. Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, 03028 Kyiv (Ukraine)

The spectral distribution of quantum detection efficiency of X- and {gamma}-ray Schottky diodes based on semi-insulating CdTe or Cd{sub 0.9}Zn{sub 0.1}Te crystals is substantiated and obtained in analytical form. It is shown that the width of the space charge region (SCR) of 6-40 {mu}m at zero bias in CdTe (Cd{sub 0.9}Zn{sub 0.1}Te) Schottky diode is optimal for detecting radiation in the photon energy range above 5-10 keV. Based on the Poisson equation, the relationship between the SCR width and the composition of impurities and the degree of their compensation are investigated. It is shown that the presence of deep levels in the bandgap leads to a considerable increase in space charge density and electric field strength near the crystal surface. However, this effect contributes a small error in the determination of the SCR width using the standard formula for the Schottky diode. It is also shown that the concentration of uncompensated impurities in CdTe and Cd{sub 0.9}Zn{sub 0.1}Te crystals within the 4 Multiplication-Sign 10{sup 11}-10{sup 13} cm{sup -3} range is optimal for the detection efficiency of X- and {gamma}-rays in the photon high-energy range. The record-high values of energy resolution have been obtained in the spectra of {sup 241}Am, {sup 57}Co, {sup 133}Ba and {sup 137}Cs isotopes measured using CdTe crystals with Schottky diodes because the concentration of uncompensated donors in the CdTe crystals (1-2) Multiplication-Sign 10{sup 12} cm{sup -3} falls on an interval of maximum detection efficiency. In the spectrum of {sup 57}Co isotope, the limiting energy resolution has been achieved.

• OSTI ID: 22102262
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 5 Vol. 113; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMERICIUM 241
BARIUM 133
CADMIUM TELLURIDES
CESIUM 137
COBALT 57
ELECTRIC FIELDS
ENERGY GAP
ENERGY RESOLUTION
GAMMA DETECTION
IMPURITIES
POISSON EQUATION
SCHOTTKY BARRIER DIODES
SEMICONDUCTOR MATERIALS
SPACE CHARGE
SPECTRA
SURFACES
X RADIATION
X-RAY DETECTION
ZINC COMPOUNDS