The operation principle, fabrication, and measurement results for a stand-alone amplifier based on impact ionization are reported. The device was built in silicon using standard microelectronic processes. Testing was performed by connecting the device to both silicon and indium-gallium-arsenide photodiodes to demonstrate its compatibility with arbitrary current sources. Preamplified leakage currents of less than 1nA were measured along with current gains greater than 100.
This paper presents an innovative solid-state current amplifier based on impact ionization. The operation principle, fabrication, and test results for this device are reported. This amplifier was built on a silicon surface using standard microelectronics processes including ion implantation. Testing was performed by connecting the device to both silicon and indium-gallium-arsenide photodiodes to demonstrate its compatibility with arbitrary current sources. Current gains above 100 along with pre-amplified leakage currents of less than 10 nA were measured.
We report the demonstration of a current amplification device, built from silicon and based on impact ionization, which can be cascaded to achieve very high gains. Arbitrary current sources including photodiodes can be interfaced with this device. Testing was done by amplifying the output signal from an independent silicon photodiode. Current gains over 600 were measured for initial photocurrents of 10 nA when two amplifying devices were cascaded together. Additionally, the gain saturation phenomenon of the amplifier due to space-charge effects is investigated. The measured gain saturation is observed to match very well with theoretical predictions. We also present guidelines for obtaining high current gain from the cascaded structure while avoiding gain saturation. Because of the low-noise gain mechanism employed, this device is of potential interest to a variety of fields requiring high-sensitivity optical or electronic detection.Index Terms-Avalanche photodiode (APD), electron multipliers, impact ionization, space charge.
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