An amorphous silicon photodiode with 2 THz gain-bandwidth product based on cycling excitation process
Abstract
Since impact ionization was observed in semiconductors over half a century ago, avalanche photodiodes (APDs) using impact ionization in a fashion of chain reaction have been the most sensitive semiconductor photodetectors. However, APDs have relatively high excess noise, a limited gain-bandwidth product, and high operation voltage, presenting a need for alternative signal amplification mechanisms of superior properties. As an amplification mechanism, the cycling excitation process (CEP) was recently reported in a silicon p-n junction with subtle control and balance of the impurity levels and profiles. Realizing that CEP effect depends on Auger excitation involving localized states, we made the counter intuitive hypothesis that disordered materials, such as amorphous silicon, with their abundant localized states, can produce strong CEP effects with high gain and speed at low noise, despite their extremely low mobility and large number of defects. Here, we demonstrate an amorphous silicon low noise photodiode with gain-bandwidth product of over 2 THz, based on a very simple structure. This work will impact a wide range of applications involving optical detection because amorphous silicon, as the primary gain medium, is a low-cost, easy-to-process material that can be formed on many kinds of rigid or flexible substrates.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 04, 2017
- Source ID
- 10.1063/1.5001170
Entities
People
- Alex Ce Zhang
- David L. Hall
- Iftikhar Ahmad Niaz
- Lujiang Yan
- Mohammad Abu Raihan Miah
- Yu-Hwa Lo
- Yu-hsin Liu
- Yugang Yu
Organizations
- Defense Advanced Research Projects Agency
- National Science Foundation
- Office of Naval Research
- University of California