Infrared imaging array based on temperature driven anisotropic optical absorption

US5488226A · kind A · utility

Assignee

• The United States of America as represented by the Secretary of the Army · US

Inventors

• Gerald J. Iafrate · Raleigh, US
• Mitra Dutta · Tinton Falls, US
• Paul H. Shen · North Potomac, US
• Michael A. Stroscio · Durham, US

Key dates

• Filing date: Nov 18, 1994
• Grant date: Jan 30, 1996
• Expiry date: Nov 18, 2014

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10N19/00
• WIPO field: Micro-structural and nano-technology
• WIPO sector: Chemistry

Abstract

An thermal imaging device having a transparent substrate, an active multiple quantum well (MQW) epilayer with bottom electrical contacts bonded to the substrate, wherein the substrate is cut such that its thermal expansion coefficient is matched or roughly matched to that of the MQW epilayer in the direction parallel to the long axis of the bottom contacts and so that the thermal expansion coefficient of the substrate is mismatched in a direction normal to the long axis of the bottom contacts. Infrared radiation incident on each unit cell of the n.times.m array will produce a temperature change .DELTA.T in the MQW which will produce stress normal to the long axis of the bottom contacts. The uniaxial stress produced by the temperature changes .DELTA.T breaks the rotation symmetry in the plane of the MQW structure. This will result in anisotropic mixing of the heavy and light holes in the MQW epilayer and thus, will result in an anisotropic excitonic absorption of the MQW epilayer, which can be detected and analyzed either electrically or optically.