Solid-state impact -ionization multiplier

2006 2006

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Abstract (summary)

This dissertation presents an innovative solid-state current amplifier based on impact-ionization. Unlike avalanche photodetectors which use the same amplification principle, this device can be integrated with any external current source. A discrete amplifier was built on a silicon surface using standard CMOS fabrication processes including lithography, oxidation, ion implantation, diffusion, chemical wet etching, metal deposition, annealing, and rapid thermal processing. Testing was performed by connecting the device to a silicon photodiode, indium-gallium-arsenide photodiodes, and a function generator 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.

This amplifier can also be cascaded to achieve very high gains similar to the photomultiplier tube but with much smaller size and no vacuum environment required. Testing was done by amplifying the output signal from an external silicon photodiode.

Current gains over 600 were measured when two amplifying devices were cascaded. Additionally, the gain saturation phenomenon of the amplifier due to the space-charge effect is investigated. The measured gain saturation is observed to match very well with the theoretical based predictions. We also present a design rule for obtaining high current gain from the cascaded structure without experiencing gain saturation.

Initial bandwidth of the SIM when connected to a silicon photodiode was measured to be about 300 kHz. As we replace the photodiode by a function generator, the bandwidth improved to 450 kHz which is the frequency limit of the system. These results were made on the first generation of SIM devices. We discovered that the space-charge resistance Rsc plays a significant role in determining frequency response. In future generations of the device, we can begin with optimizing the device geometry to reduce this resistance. Also, we can reduce the size of the metal pad and increase the oxide layer thickness to further minimize the device capacitance for faster response.

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.

Indexing (details)

Electrical engineering;
0544: Electrical engineering
0752: Optics
Identifier / keyword
Applied sciences; Pure sciences; Current gain; Impact-ionization; Multiplier; Solid-state
Solid-state impact -ionization multiplier
Lee, Hong-Wei
Number of pages
Publication year
Degree date
School code
DAI-B 67/01, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
9780542536403, 0542536404
Hawkins, Aaron R.
Brigham Young University
University location
United States -- Utah
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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