In this paper we report a high performance 2-stack, 3-color quantum well infrared photodetector (QWIP) composed of InGaAs/AlGaAs QWIP and an InGaAs/AlGaAs/InGaAs triple- coupled (TC-) QWIP grown on the GaAs substrate for the mid- and long-wavelength (MW/LW) infrared (IR) detection. The basic device structure consists of a MWIR QWIP stack with 3 periods of 43 Angstroms In0.3Ga0.7As quantum well and an undoped 300 Angstroms Al0.3Ga0.7As barrier and a LWIR TC-QWIP stack with 5 periods of 65 Angstroms In0.18Ga0.82As quantum well (QW) and two undoped 60 Angstroms In0.05Ga0.95As Qws separated by 20 Angstroms Al0.08Ga0.92As barriers. The TC-QWIP stack has two response peaks, which are voltage-tunable from 9.2micrometers to 10 micrometers and 12micrometers to 12.2micrometers by the applied bias, respectively. For the LWIR TC-QWIP, a maximum responsivity of 1.96A/W at 12micrometers was obtained at T=40K, and a maximum detectivity of (Formula available in paper) was obtained at Vb=-1.7V, λp=12micrometers , and T=20K. As for the MWIR QWIP stack excellent responsivity at the peak wavelength of λp=5.1micrometers was obtained up to 120 K.
Typical quantum well infrared photodetectors (QWIPs) exhibit rather narrow spectral bandwidth of 1 to 2 micrometer. For certain applications, such as spectroscopy, sensing of a broader range of infrared radiation is highly desirable. In this work, we report the design of five broadband (BB-) QWIPs sensitive over the 7 to 14 micrometer spectral range. Three n- type BB-QWIPs consisting of three, four, and five quantum wells of different thickness and/or composition in a unit cell, which are then repeated 20 times for the three and four quantum wells (QW) devices and 3 times for the five QWs device to create the BB-QWIP structures, are demonstrated. The three- well n-type InxGa1-xAs/AlyGa1-yAs BB-QWIP is designed to have a response peak at 10 micrometer, with a FWHM bandwidth that varies with the applied bias. A maximum bandwidth of (Delta) (lambda) /(lambda) p equals 21% was obtained for this device at Vb equals -2 V. The four- well n-type InxGa1-xAs/GaAs BB-QWIP not only exhibits a very large responsivity of 2.31 A/W at 10.3 micrometer and Vb equals +4.5 V, but also achieves a broader bandwidth of (Delta) (lambda) /(lambda) p equals 29% than the three-well device. The five-well n-type InxGa1- xAs/GaAs BB-QWIP has achieved a FWHM bandwidth of (Delta) (lambda) /(lambda) p equals 28% at Vb equals 1.75 V. In addition, two p-type InxGa1-xAs/GaAs BB-QWIPs with variable well thickness and composition, sensitive in the 7 - 14 micrometer spectral range, are also demonstrated. The variable composition p-type BB-QWIP has a very large FWHM bandwidth of (Delta) (lambda) /(lambda) p equals 48% at Vb equals -1.5 V and T equals 40 K. The variable thickness p- type BB-QWIP was found to have an even broader FWHM bandwidth of (Delta) (lambda) /(lambda) p equals 63% at Vb equals 1.1 V and T equals 40 K, with a corresponding peak responsivity of 25 mA/W at 10.2 micrometer. The results reveal that p-type BB- QWIPs have a broader and flatter spectral bandwidth but lower responsivity than that of n-type BB-QWIPs under similar operating conditions.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.