Modulation-Doped Heterostructure-Thermopiles for Uncooled Infrared Image-Sensor Application

Masayuki ABE

Summary :

Novel thermopiles based on modulation doped AlGaAs/InGaAs, AlGaN/GaN, and ZnMgO/ZnO heterostructures are proposed and designed for the first time, for uncooled infrared image sensor application. These devices are expected to offer high performances due to both the superior Seebeck coefficient and the excellently high mobility of 2DEG and 2DHG due to high purity channel layers at the heterojunction interface. The AlGaAs/InGaAs thermopile has the figure-of-merit Z of as large as 1.110^-2/K (ZT = 3.3 over unity at T = 300 K), and can be realized with a high responsivity R of 15,200 V/W and a high detectivity D^* of 1.810⁹ cmHz^1/2/W with uncooled low-cost potentiality. The AlGaN/GaN and the ZnMgO/ZnO thermopiles have the advantages of high sheet carrier concentration due to their large polarization charge effects (spontaneous and piezo polarization charges) as well as of a high Seebeck coefficient due to their strong phonon-drag effect. The high speed response time τ of 0.9 ms with AlGaN/GaN, and also the lower cost with ZnMgO/ZnO thermopiles can be realized. The modulation-doped heterostructure thermopiles presented here are expected to be used for uncooled infrared image sensor applications, and for monolithic integrations with other photon detectors such as InGaAs, GaN, and ZnO PiN photodiodes, as well as HEMT functional integrated circuit devices.

• Publication: IEICE TRANSACTIONS on Electronics Vol.E93-C No.8 pp.1302-1308
• Publication Date: 2010/08/01
• Online ISSN: 1745-1353
• DOI: 10.1587/transele.E93.C.1302
• Type of Manuscript: Special Section PAPER (Special Section on Heterostructure Microelectronics with TWHM 2009)
• Category: III-V Heterostructure Devices

Authors

Masayuki ABE

Keyword

Seebeck effect,  heterostructure thermopile,  infrared image sensor,  AlGaAs/InGaAs,  AlGaN/GaN,  ZnMgO/ZnO