Superconducting nanowire single-photon detectors and sub-10-nm lithography

Superconducting nanowire single-photon detectors (SNSPDs) are useful in applications such as free-space optical communications to achieve high-speed data transfer across vast distances with minimum transmission power. In this and other applications, SNSPDs with high detection efficiencies are required. To this end, we designed and fabricated an integrated optical cavity and anti-reflection coating that enhanced the detection efficiency of SNSPDs by almost threefold to current record values of 57% at 1550 nm wavelength. We also improved our understanding of SNSPDs by modeling the electro-thermal response of the detector. This model showed that, beyond the initial formation of a photon-induced resistance across the nanowire, Joule heating results in the growth of the resistive segment. While simple, this model was useful in designing SNSPDs that reset more quickly, and also in explaining an undesirable behavior of the SNSPDs where the devices latch into a resistive state and fail to reset. Like many other devices, such as transistors, SNSPDs would benefit from device miniaturization: SNSPDs with narrower nanowires have higher detection efficiencies and increased sensitivity to low-energy photons. In this thesis, we investigated the resolution performance of electron-beam lithography (EBL) by first improving the contrast performance of hydrogen silsesquioxane (HSQ) negative-tone resist. The contrast of HSQ was improved by adding NaCl salt to an aqueous NaOH developer solution. With this improvement, we achieved a high-resolution electron-beam lithography process capable of patterning structures at 9-nm-pitch dimensions.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Yang, Joel K. (Joel Kwang wei)

Advisor dc:contributor.advisor

• Karl K. Berggren.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/53307

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/53307