BIOMEDICAL IMAGING: Inexpensive approach speeds photodetector used in medical imaging

Sept. 25, 2013
An amorphous silicon (a-Si) metal-semiconductor-metal heterojunction photodetector with added molybdenum disulfide (MoS2) could boost the speed of medical imaging for minimal cost. MoS2 is sold as a lubricant in auto-parts shops.

An amorphous silicon (a-Si) metal-semiconductor-metal heterojunction photodetector with added molybdenum disulfide (MoS2) could boost the speed of medical imaging for minimal cost.1 MoS2 is sold as a lubricant in auto-parts shops.

Many photodetectors in large-area imaging devices use a-Si because it absorbs light well and is relatively inexpensive to process. But because the material inherently prevents fast, ordered movement of electrons, it operates more slowly, and thus allows greater exposure to radiation. The standard approach to improving performance has involved additional high-temperature processing, which adds to the cost of the imaging device.

University of California, Berkeley engineers Sayeef Salahuddin and Mohammad Esmaeili-Rad devised their solution by pairing a thin film of MoS2 with a sheet of a-Si. By forming a diode with the a-Si, the MoS2 allows the photogenerated electrons that it collects to travel through the a-Si 10 times faster. The detector has a photoresponsivity of 210 mA/W for green light, which is two to four times higher than usual for a-Si devices.

The researchers say that because these materials are easy to handle and inexpensive, the cost of speeding up photodetectors would be minimal. Unlike conventional semiconductors like Si, MoS2 consists of individual nanosheets that can be torn off like pages in a book. These sheets can be used to make thin, novel electronic devices or to improve existing ones.

1. M. R. Esmaeili-Rad and S. Salahuddin, Sci. Rep., 3, 2345 (2013); doi:10.1038/srep02345.

Sponsored Recommendations

Hexapod 6-DOF Active Optical Alignment Micro-Robots - Enablers for Advanced Camera Manufacturing

Dec. 18, 2024
Optics and camera manufacturing benefits from the flexibility of 6-Axis hexapod active optical alignment robots and advanced motion control software

Laser Assisted Wafer Slicing with 3DOF Motion Stages

Dec. 18, 2024
Granite-based high-performance 3-DOF air bearing nanopositioning stages provide ultra-high accuracy and reliability in semiconductor & laser processing applications.

Steering Light: What is the Difference Between 2-Axis Galvo Scanners and Single Mirror 2-Axis Scanners

Dec. 18, 2024
Advantages and limitations of different 2-axis light steering methods: Piezo steering mirrors, voice-coil mirrors, galvos, gimbal mounts, and kinematic mounts.

Free Space Optical Communication

Dec. 18, 2024
Fast Steering Mirrors (FSM) provide fine steering precision to support the Future of Laser Based Communication with LEO Satellites

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!