Tuning Amorphous Selenium Composition with Tellurium to Improve Quantum Efficiency at Long Wavelengths and High...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Detector Physics

Background:

• Amorphous selenium (a-Se) is a key photoconductor for UV and X-ray detectors.
• Applications in medical imaging, life science, and physics require broad spectral coverage.
• Optimizing a-Se properties for high-performance detectors is an ongoing research area.

Purpose of the Study:

• To systematically investigate the optical and electrical properties of amorphous selenium alloyed with tellurium (a-Se_1-Te).
• To evaluate the performance of a-Se_1-Te devices, including mobilities and conversion efficiencies, under high electric fields.
• To understand the role of tellurium alloying and defect states in enhancing detector performance.

Main Methods:

• Utilized density functional theory (DFT) simulations to model material properties.
• Conducted experimental studies on a-Se_1-Te (x = 0, 0.03, 0.05, 0.08) devices.
• Measured hole and electron mobilities, conversion efficiencies, and band gaps as a function of applied electric field.

Main Results:

• Reported mobilities and conversion efficiencies for Se-Te alloys at high electric fields (>10 V/μm).
• Demonstrated the recovery of quantum efficiency in Se-Te alloy devices.
• Compared experimental results to the Onsager model, highlighting field-dependent thermalization length and defect state influence.

Conclusions:

• Tellurium alloying significantly impacts the optical and electrical properties of amorphous selenium.
• Se-Te alloys exhibit enhanced performance, including quantum efficiency recovery, at high electric fields.
• The findings provide crucial insights into defect states and thermalization length, advancing the development of next-generation radiation detectors.