Characterization of the metal–semiconductor interface of gold contacts on CdZnTe formed by electroless deposition

Bell, Steven; Baker, Mark; Duarte, Diana D.; Schneider, Andreas; Seller, P.; Sellin, P.J.; Veale, Matthew C.; Wilson, Matthew D.

doi:10.1088/0022-3727/48/27/275304

Cited by 21 publications

(9 citation statements)

References 56 publications

(73 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At low voltages (the inset of Fig. 4 ), both samples highlight a “S” shape curve, typical of metal–semiconductor–metal (MSM) contacts with two back-to-back Schottky barriers 24 – 26 . In this region, the current is dominated by the bulk resistivity and the contact resistance.…”

Section: Resultsmentioning

confidence: 99%

Improved electroless platinum contacts on CdZnTe X- and γ-rays detectors

Bettelli

Amadé

Zanettini³

et al. 2020

Sci Rep

View full text Add to dashboard Cite

platinum is a promising candidate for the realization of blocking electrical contacts on cadmium-zinctelluride (cdZnte or cZt) radiation detectors. However, the poor mechanical adhesion of this metal often shortens the lifetime of the final device. In this work, a simple and effective procedure to obtain robust platinum contacts by electroless deposition is presented. Microscopical analysis revealed the final thickness and composition of the contact layer and its adhesion to the bulk crystal. The blocking nature of the Pt-CdZnTe junction, essential to obtain low noise devices, was confirmed by current-voltage measurements. the planar pt-cdZnte-pt detectors showed good room temperature spectroscopic performance with energy resolution of 4% (2.4 keV) and 3% (3.7 keV) FWHM at 59.5 and 122.1 keV, respectively. Finally, we showed, for the first time, that platinum contacts allow the estimation of the carrier lifetime and mobility of both holes and electrons by using current transient measurements. This demonstrated the optimal hole extraction capability of such contacts. CdTe and CdZnTe (CZT) have proven to be excellent materials for room temperature X-ray and gamma-ray detectors and they are gradually replacing other sensing systems in many applications. Electrical contacts on such detectors need to be customised according to the final purpose of the device and engineered depending on the properties of the starting material such as work function and bulk resistivity. A great interest has been addressed to platinum metal contacts 1-3 because Pt work function (~ 5.6 eV) leads to the formation of a high Pt-CZT Schottky barrier which limits the carrier injection and thus the leakage current. This is the reason why blocking contacts are usually adopted to realize high-resolution spectrometers 4. Electroless deposition technique is vastly used to deposit contacts on II/VI materials. The reason lies in its simplicity since no specific or expensive laboratory equipment is required. This method consists in the spontaneous reaction of the metal in salt form dissolved in a proper solvent with the detector material. The reaction takes place without the use of any external electric power and allows to realize chemically stable and reproducible contacts. Moreover, the oxide formation at the metal/semiconductor interface is minimised since contacts are realised immediately after the polishing step, hence reducing the air exposition of the highly reactive surface. This is crucial to reduce the effect of the oxide layer on the leakage current and charge collection efficiency. Lastly, fine tuning of electroless deposition parameters allows to control the final quality of the metallic layer in term of thickness and homogeneity. In this work, Pt contacts have been deposited by means of a electroless deposition technique based on alcoholic solution. The CdZnTe detectors have been realised and characterised thorough mechanical, structural, electrical, and spectroscopic analysis. This study is focused on explaining the role of the metal/se...

show abstract

Section: Resultsmentioning

confidence: 99%

Improved electroless platinum contacts on CdZnTe X- and γ-rays detectors

Bettelli

Amadé

Zanettini³

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…During the fabrication process of CdZnTe detectors, such as surface treatment and electrode preparation, interfacial layers will be inevitably introduced. [ 20 ] To study the influence of interfacial layer on the device performance, the space charge concentration, carrier concentration, and internal electric field distribution at 100 V bias are simulated. The value of C 2 corresponding to the different interface layers is shown in Table 1 .…”

Section: Resultsmentioning

confidence: 99%

Effect of Ar Plasma Treatment on the Interface and Performance of CdZnTe Detectors

Cao

Zhang

Wang

et al. 2023

Cryst. Res. Technol.

View full text Add to dashboard Cite

The performance of CdZnTe detectors is not only influenced by the growth of crystal, but also by the quality of the interface layer between the crystal and the electrode. A model of CdZnTe detector with metal–semiconductor–metal structure is developed to investigate the effects of the interface on the space charge and electric field distribution. Atomic force microscopy, current–voltage (I–V) analysis, and energy spectra under 241Am irradiation are adopted to investigate the effects of argon (Ar) plasma treatment on the interface and performance of CdZnTe detectors experimentally. The simulation results show that the interface layer with low density of surface state and thin thickness can form a more uniform space charge and electric field distribution. Due to the decrease of voltage drop across the interface, the leakage current at 200 V of CdZnTe detector with Ar plasma treatment is reduced from 159 to 44 nA cm−2, and the full‐width at half‐maximum under 241Am is improved from 9.3% to 8.2%, as compared to conventional Br‐MeOH treatment.

show abstract

“…The crystals were prepared by lapping with 3 µm alumina slurry, followed by a two stage mechanical polish with 0.3 µm and 0.05 µm alumina slurry. It was decided not to chemo-mechanically polish the CdZnTe in order to avoid associated interface non-uniformity and the development of the orange-peel effect [20].…”

Section: Experimental Procedures 21 Detector Fabricationmentioning

confidence: 99%

Performance comparison of small-pixel CdZnTe radiation detectors with gold contacts formed by sputter and electroless deposition

et al. 2017

View full text Add to dashboard Cite

A: Recent improvements in the growth of wide-bandgap semiconductors, such as cadmium zinc telluride (CdZnTe or CZT), has enabled spectroscopic X/γ-ray imaging detectors to be developed. These detectors have applications covering homeland security, industrial analysis, space science and medical imaging. At the Rutherford Appleton Laboratory (RAL) a promising range of spectroscopic, position sensitive, small-pixel Cd(Zn)Te detectors have been developed. The challenge now is to improve the quality of metal contacts on CdZnTe in order to meet the demanding energy and spatial resolution requirements of these applications. The choice of metal deposition method and fabrication process are of fundamental importance. Presented is a comparison of two CdZnTe detectors with contacts formed by sputter and electroless deposition. The detectors were fabricated with a 74 × 74 array of 200 µm pixels on a 250 µm pitch and bump-bonded to the HEXITEC ASIC. The X/γ-ray emissions from an 241 Am source were measured to form energy spectra for comparison. It was found that the detector with contacts formed by electroless deposition produced the best uniformity and energy resolution; the best pixel produced a FWHM of 560 eV at 59.54 keV and 50% of pixels produced a FWHM better than 1.7 keV. This compared with a FWHM of 1.5 keV for the best pixel and 50% of pixels better than 4.4 keV for the detector with sputtered contacts.

show abstract

Characterization of the metal–semiconductor interface of gold contacts on CdZnTe formed by electroless deposition

Abstract: A multi-technique characterization of electroless gold contacts on single crystal CdZnTe radiation detectors S J Bell, M A Baker, H Chen et al. -Performance comparison of small-pixel CdZnTe radiation detectors with gold contacts formed by sputter and electroless deposition

Cited by 21 publications

References 56 publications

Improved electroless platinum contacts on CdZnTe X- and γ-rays detectors

Improved electroless platinum contacts on CdZnTe X- and γ-rays detectors

Effect of Ar Plasma Treatment on the Interface and Performance of CdZnTe Detectors

Performance comparison of small-pixel CdZnTe radiation detectors with gold contacts formed by sputter and electroless deposition

Contact Info

Product

Resources

About