A picosecond response photodiode for optical and x-ray timing experiments

Fusion and high energy density physics (HED) facilities perform ultra-fast timing experiments that require good quantum efficiency (QE) in deep UV and x-ray regimes. As an example, beam timing measurements at free electron laser (FEL) facilities monitor timing for electron bunch pulses with ~ 100 kHz repetition rates in laser-driven shock, plasma, and optical/UV pump-probe experiments. These measurements require detector rise-fall times to be below 50 ps to monitor coarse timing. Device size is another important factor, particularly in the crowded and complex target chambers of fusion facilities. The need for robust, condensed packaging, and picosecond time resolution extends to fields of laser characterization, synchrotrons, and high-speed communication. There is not currently a fast photodiode available in the market with a UV/x- ray response time < 50 ps. A photodiode based off of a metal semiconductor metal (MSM) technology will be fabricated, tuned and tested to produce < 50 ps response times with high QE for ultra violet and x-ray wavelengths. The QE of the device will be tuned by researching different semiconductor materials with different dopant levels and novel electrode structures. The primary objective of the proposed program is to determine the feasibility of commercializing a tunable wavelength fast photodiode to fill the market need for improved ultra-fast detection in UV and x-ray ranges in FES applications. A study of the laboratory research and development completed to-date at a partner universities laboratory will be conducted and a plan for the development of a commercial-ready UV x-ray fast photodiode will be produced. This will include evaluation of mechanical and electrical packaging, and sensor fabrication. The company will design a packaging concept for the commercial diode based on this assessment. A robust and commercially supported fast photodiode with the current proven performance specifications will enable x-ray FEL facilities to conduct the timing measurements they need. In addition, it is anticipated that the research vein of this project will produce devices with a standard package, but interchangeable diode material that will satisfy a variety of experimental conditions (e.g. energy ranges beyond the UV into IR or x-ray regimes). These advanced features combined with the core timing, noise, and wavelength features of this device will provide the scientific community with a robust product to rely on for testing like pulse time monitoring and pump-probe experiments.