Simulation of CVD diamond-based high speed near-infrared photodetectors

• A high speed near-infrared CVD diamond Schottky diode photodetector is simulated.
• Modulation doping of the CVD diamond depletion layer is considered.
• Modulation doping thins Schottky barrier and increases tunneling photocurrent.
• Modulation doping increases device speed by decreasing speed-limiting capacity.

A near-infrared photodetector on an unbiased p-type CVD diamond Schottky diode is considered and simulated in details. As a diamond-based device, it possesses radiation and chemical endurance and a large hole saturation velocity, determining its potential for high-speed operation. To raise the photodetector sensitivity by thinning the Schottky barrier and thereby increasing its tunneling transparency for holes an alternative to the high homogeneous depletion layer doping is investigated. It consists in the division of the depletion layer into two parts: the thick low-doped part and the highly-doped part (a delta-layer), placed at the depletion layer interface with a metal. It is shown that such doping profile is more advantaged than a high homogeneous doping as it allows to decrease the speed-limiting device capacitance by more than 5 times while maintaining the same device sensitivity.

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