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Modeling Dark Current Conduction Mechanisms and Mitigation Techniques in Vertically Stacked Amorphous Selenium-Based
Le Thanh Triet Ho1, Atreyo Mukherjee1, Dragica Vasileska2
1Department of Electrical Engineering, College of Engineering and Applied Sciences, Stony Brook University, Stony Brook, New York 11794, United States.
ACS Applied Electronic Materials
|May 23, 2022
Summary
Amorphous selenium detectors offer a solid-state alternative to photomultiplier tubes for low-light detection. Optimizing hole blocking layers is crucial to prevent breakdown and enhance performance in these avalanche devices.
Area of Science:
- Materials Science
- Solid-State Physics
- Detector Technology
Background:
- Amorphous selenium (a-Se) shows promise for low-light detection, potentially replacing vacuum photomultiplier tubes (PMTs).
- Avalanche detectors based on a-Se could achieve PMT-comparable gains, but are hindered by inefficient hole blocking layers (HBLs) leading to breakdown.
- Understanding transport characteristics and controlling electrical hot spots are vital for improving avalanche a-Se device performance.
Purpose of the Study:
- To investigate conduction mechanisms in a-Se based detectors.
- To identify strategies for preventing dielectric breakdown in a-Se avalanche detectors.
- To optimize the design of hole blocking layers for improved device stability.
Main Methods:
- Utilized Atlas SILVACO simulations to model conduction mechanisms including space-charge-limited current, bulk thermal generation, Schottky emission, Poole-Frenkel activated mobility, and hopping conduction.
- Incorporated simulation parameters derived from experimental data and first-principle calculations.
- Validated theoretical models against experimental steady-state dark current densities in both avalanche and non-avalanche a-Se detectors.
Main Results:
- Identified key conduction mechanisms governing device behavior.
- Demonstrated that a high-permittivity noninsulating material is necessary to reduce electric field at the electrode/HBL interface.
- Showed that preventing electrode injection and subsequent Joule heating prevents crystallization and early dielectric breakdown.
Conclusions:
- High-permittivity materials are essential for maintaining bulk thermal generation-limited dark currents in a-Se detectors.
- Reducing electric field at the electrode/HBL interface prevents hot spots and premature device failure.
- This approach enables the development of more stable and reliable a-Se avalanche detectors for low-light applications.
