Numerical Study of Dual band (MW/LW) IR Detector for Performance Improvement

Abstract

In the present study, an extensive numerical analysis has been performed and an effort has been made to understand the underlying physics, which is presently unclear for researchers for development of third generation FPA infrared detectors based on HgCdTe material. To reduce technology development cost associated with dual band photodetector for operation at MWIR and LWIR regions, a 2D theoretical model has been proposed including all the relevant physics. The structure under present study considers back-to-back diode structures to detect simultaneous MW/LW operative wavelength by changing the biasing polarity of the diodes. The optimum electrical and optical outputs from dual band detector have been achieved through performing design of experiments. The coupled basic semiconductor equations including nonlinear continuity, transport and Poisson's equations have been solved to achieve electrical (I-V) characteristics under no bias condition and modern optics equations has been coupled to semiconductor equations to obtain optical characteristics. The quantum efficiency of both detectors has been computed and compared with experimental results. The computed results obtained on the basis of proposed model accurately matches with the experimental results reported by others researcher. The results exhibit the quantum efficiencies, QE MW =95 per cent and QE LW =74.5 per cent, respectively.

Bilayer graphene/HgCdTe based very long infrared photodetector with superior external quantum efficiency, responsivity, and detectivity

“…The p + -BLG/n-Hg 0.8133 Cd 0.1867 Te photodetector is electrically characterized by solving continuity, carrier transport and Poisson equations with optimized boundary conditions as approximated by Boltzmann's transport model. 15 Here, BLG is considered as 3D in nature analogous to earlier reported studies demonstrating the integration of multilayer graphene with other conventional semiconductors which couples 2D transport equations to 3D equations. 67 A 2D semiconductor material has one physical dimension of the order of Fermi wavelength λ F .…”

“…The doping and carrier densities are evaluated using Fermi-Dirac statistics. 15,24,78 The performance of the photodetector at 77 K is evaluated analytically for the operation at the wavelength of 20.6 mm. The photons having energy greater than the bandgap create electron-hole pairs in the lightly doped n-region.…”

“…87,88 For the photon energy E p < E gn (tail region) and E p > E gn (Kane region), the absorption coefficient is approximated by: a n ðlÞ ¼ ( a 0 e ðd=KTÞðEpÀE 0 Þ E p \E gn ðx; TÞ a g ðx; TÞe bðx;TÞðEpÀEgnðx;TÞÞ E p . E gn ðx; TÞ (15) where a 0 ¼ e (À18.5+45.68x) ; E 0 ¼ À0.355 + 1.77x the tting parameters which vary with x composition and…”

“…12 The potential applications of IR photodetectors include biomedical and thermal imaging, gas sensing, night vision, spectroscopy, and free space communication etc. 4,[13][14][15] Rapid advances are being made in developing inexpensive narrow bandgap semiconductor photodetectors with improved sensitivity and longer wavelengths. As a result, low dimensional structures, including quantum-well, quantum-dot, and quantum-wire, based IR photodetectors are reported with improved performances, but with expensive fabrication processes.…”

“…[16][17][18][19] On the other hand, the low leakage current, tunable bandgap, better stability, low thermal generation rate and relatively high absorption coefficient make the ternary alloy mercury cadmium telluride (MCT: Hg 1Àx Cd x Te) a suitable material for high performance IR detectors. 12,14,[20][21][22] So far, numerous Hg 1Àx Cd x Te-based IR photodetectors with different congurations such as p-n, 23,24 p-i-n, 14,25 dual band IR detector, 15,26 and avalanche photodiode 27 have been reported at cryogenic temperatures. The high dark current limited by Auger recombination processes and low temperature operations are the major disadvantage of MCT based IR photodetector.…”