Modeling Dark Current Conduction Mechanisms and Mitigation Techniques in Vertically Stacked Amorphous Selenium-Based Photodetectors

Le Thanh Triet Ho, Atreyo Mukherjee, Dragica Vasileska, John Akis, Jann Stavro, Wei Zhao, Amir H. Goldan

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Amorphous selenium (a-Se) with its single-carrier and non-Markovian, hole impact ionization process can revolutionize low-light detection and emerge to be a solid-state replacement to the vacuum photomultiplier tube (PMT). Although a-Se-based solid-state avalanche detectors can ideally provide gains comparable to PMTs, their development has been severely limited by the irreversible breakdown of inefficient hole blocking layers (HBLs). Thus, understanding of the transport characteristics and ways to control electrical hot spots and, thereby, the breakdown voltage is key to improving the performance of avalanche a-Se devices. Simulations using Atlas, SILVACO, were employed to identify relevant conduction mechanisms in a-Se-based detectors: space-charge-limited current, bulk thermal generation, Schottky emission, Poole-Frenkel activated mobility, and hopping conduction. Simulation parameters were obtained from experimental data and first-principle calculations. The theoretical models were validated by comparing them with experimental steady-state dark current densities in avalanche and nonavalanche a-Se detectors. To maintain bulk thermal generation-limited dark current levels in a-Se detectors, a high-permittivity noninsulating material is required to substantially decrease the electric field at the electrode/hole blocking layer interface, thus preventing injection from the high-voltage electrode. This, in turn, prevents Joule heating from crystallizing the a-Se layer, consequently avoiding early dielectric breakdown of the device.

Original languageEnglish (US)
Pages (from-to)3538-3546
Number of pages9
JournalACS Applied Electronic Materials
Issue number8
StatePublished - Aug 24 2021


  • Silvaco
  • TCAD modeling
  • amorphous selenium
  • avalanche photodetectors
  • modeling disordered materials

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Electrochemistry


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