Voltage-controlled tunable GaAs/AlGaAs multistack quantum well infrared detector

Abstract

We describe a new type of intersubband GaAs/AlGaAs infrared detector consisting of three stacks of quantum wells; the quantum wells in a given stack-are identical, but are different from stack to stack. Each stack is designed to yield an absorption and a photoresponse at a different peak wavelength. The resulting device is an infrared detector which can operate in a number of modes. Among the features of this device are a wide-band detection domain, a tunable response and excellent responsivities and noise figures. The tunable operation includes a sharp peak-switching response which follows the formation, expansion, and readjustment of electric field domains within the multiquantum well region.Intersubband quantum well detectors have recently been the subject of a considerable research effort;ld properties important for many applications are a wide spectral response,7 preferably over the atmospheric window 8-12 pm and tunability of the peak wavelength.s-"We report here on the operation of a new type of bound-to-continuum GaAs infrared detector, consisting of three different stacks of quantum wells arranged in series. All the wells in a given stack are identical, but each stack is designed for absorption and detection at a different wavelength, featuring distinct well widths and barrier heights.The detector can operate in one of a number of modes. At forward and low bias voltages, the response peaks at a single wavelength ( -1400 cm-') and the device functions as a standard bound-to-continuum infrared detector."'3 When exceeding a temperature-dependent critical applied voltage, the detector's spectral response switches to a different peak wavelength ( -1140 cm -'), while the detection at the previous peak is significantly reduced. At a reverse bias the detection is again centered on the higher energy peak ( -1400 cm-') up to a specific applied voltage; for moderately higher voltages, two peaks yield a significant photoresponse. At still higher values of the reverse voltage a third response peak appears, which results in operation as a wide-band detector. These features are accompanied by good responsivity and detectivity figures.The structure was grown by molecular beam epitaxy on a semi-insulating GaAs substrate. The superlattice, clad by two n-doped contact layers, consisted of three stacks of 25 quantum wells each; the first 25 wells were 3.9 nm wide and were separated by Alo,3sGac62As barriers; the second stack consisted of 25 quantum wells 4.4 nm wide with Alo,30Ga,,70As barriers; the last stack had 25 wells 5.0 nm wide and Alo.,,Gac76As barriers. All the barriers were 44 nm long; the wells and the contacts were uniformly doped with Si to n=4X lOI cmA3.The absorption at zero field and room temperature is shown in Fig.

AlGaN based III-nitride tunnel barrier hyperspectral detector: Effect of internal polarization

“…3,6,7,11 Many efforts have been made to achieve tunable detection of mid-infrared (MIR) radiation using MEMS based Fabry-Perot cavity detectors [12][13][14][15][16] and quantum wells (QWs) based intersubband photodetectors. [17][18][19][20][21] MEMS based detectors use electrically tunable mirrors to dynamically control the length of the cavity and, hence, the resonance wavelength and an IR photodetector to detect the resonant radiation. MIR QW-based detectors utilize photoexcitation across the intersubband energies as the detection mechanism.…”

“…In some cases, bias dependent selection of a QW stack from a series of QW stacks results in tuning of the detector response. 21 Resonant tunneling through a QW can also be used for tunable MIR-FIR detection, where the resonant tunneling energy can be tuned by varying the potential drop across the QWs. 22,23 In contrast to THz, FIR, and MIR radiation, only few studies address the detection tunability in the UV-visible region.…”

Voltage-tuning in multi-color quantum well infrared photodetector stacks

“…Gravé et al first described such a QWIP-stack, with the voltage tunability accomplished by high-low field domain formation due to negative differential resistance in the tunneling regime. 9,10 The multi-color QWIP capability was expanded to cover both the 8-14 and 3-5 m atmospheric windows by Tsai et al 11 and Wang et al, 12 who also employed QWIP stacks, but in which the spectral response of one QWIP was shifted to the mid-infrared using InGaAs wells or AlAs cladding layers. However, in all of these stacked QWIP studies the complicated device physics will make optimized, reliable voltage tuning a challenge.…”

A two-stack indirect-barrier/triple-coupled quantum well infrared detector for mid-wavelength and long-wavelength infrared dual band detection

“…[6][7][8][9][10] In this letter, we report a voltage-tunable two-stack QWIP using a GaAs/ Al 0.55 Ga 0.45 As indirect-barrier ͑IB͒ QWIP 11 for the MWIR stack and an In 0.05 Ga 0.95 As/GaAs/Al 0.21 Ga 0.79 As triplecoupled ͑TC͒ QWIP 12 for the LWIR stack. A wide variety of QWIPs have been studied using two or three stacks, asymmetric coupled quantum wells ͑QWs͒ with graded barriers, and symmetric quantum wells to achieve detection of several IR radiation wavelengths in the MWIR and LWIR bands.…”