The goal of this award is to develop room-temperature operation single-photon photodetectors utilizing a structure of nanoparticle super-gated organic field effect transistors. Such photodetectors will use the incident photons as a switching valve to control the current flowing through the transistors. Light absorbing nanoparticles will be sandwiched between two gate dielectric layers to tune the source-drain output current of the transistors. The thickness of a second dielectric layer will be controlled to be very small so that photo-generated electrons in the nanoparticles can cause a dramatic variation of the hole transport behavior in the semiconductor channel by the columbic interaction between the electrons and holes. Therefore, one absorbed photon in the nanoparticles can cause a large output current variation in the transistor, which will realize huge apparent gain for single photon detection applications. The sensitivity of present photodectors will be improved with optimized semiconductor channel materials, device structure parameters, and the size of the transistor detector will be scaled down for single photon detection.
If successful, this project will yield a new generation of low cost, disposable, uncooled single-photon detectors with unprecedented performance over traditional single photon detectors, such as photomultiplier tubes or avalanche photodiodes. The super-gating detection mechanism and device structure will also establish the platform for single photon detection of very weak radiation from a broad spectrum from near infrared to ultraviolet as well as high energy radiation such as X-ray. The application of this type of photodetector in sensor array will enable higher resolution images because of the increased fill factor of each pixel. The application of such high sensitivity photodetectors in medical devices, such as computerized tomography scanners, would reduce the radiation dose exposed to the patient.
