The polarity inversion of laser beam induced current (LBIC) signal at low temperature and high
laser power density in As-doped p-type HgCdTe is investigated in this paper. It is found that the
polarity of LBIC signal reverses at 87 K compared to that at 300 K and the high laser power density is
also an important factor in inducing the LBIC signal reverse. The results demonstrate that the shape of
the LBIC signal profile is strongly dependent on the temperature of the device and the laser irradiation.
To provide a reasonable analysis for this interesting fact, a photocarrier spreading mode is presented in
this paper.
In this paper, the physical mechanism of unipolar barrier structures is elaborated for dark current
suppression. To better understand the performance characteristics of the devices and optimize the
structures, we have performed numerical drift-diffusion simulations of both n-side and p-side InAs
based unipolar barrier photodiodes with AlAs0.18Sb0.82 barriers, as well as conventional pn junction
detectors. Numerical simulation was used to calculate the current-voltage (I-V) characteristic and R0A
values for InAs unipolar barrier photodiodes and traditional pn junction photodiodes. The performances
of different device structures have been investigated for temperatures from 150 K to 350 K. Comparing
to conventional devices, the unipolar barrier device has shown significant performance improvement.
We report on the temperature-dependent extension of n-type inversion regions in mercury cadmium telluride (HgCdTe) photodiodes at low temperatures (87 K) compared to inversion regions at room temperature (300 K). Laser-beam-induced-current (LBIC) measurement techniques are used to obtain the photosensitive area extensions of n-type inversion in HgCdTe photodiodes for typical n+-on-p HgCdTe photovoltaic IR detectors. The effect of temperature on the extension of n-type conversion region is investigated by considering the sign of the LBIC signal. Theoretical results show that the hole concentration decreases in multidoped HgCdTe due to the freeze-out effect as the temperature decreases. Consequently, hole concentration is much lower than electron concentration at 87 K. The n-type inversion region extension is shown to be caused with the p-to-n type conversion.
The optical bandgap and photoresponse characteristics of middle-wavelength infrared (MWIR) mercury-cadmium-telluride (HgCdTe) photodiodes have been performed based on a self-consistent solution of the Poisson's equation, the electron/hole continuity equations, and three-generation-recombination processes as Auger, Shockley-Read-Hall and optical generation recombination. Three different carrier-density approximations: (i) parabolic conduction-band approximation, (ii) Bebb's nonparabolic expression, and (iii) Harman's nonparabolic approximation, are proposed to calculate the optical bandgap and photoresponse of MWIR HgCdTe photovoltaic devices by considering the carrier degeneracy and the nonparabolic conduction band. It is found that omitting nonparabolic effect can lead to an enormous deviation in the simulation result, especially for heavily doped HgCdTe devices. On the basis of the calculated results of photoresponse, the parabolic conduction-band and Harman's nonparabolic approximations can lead to the response peak shift to short and long wavelengths, respectively.
This paper reports on the temperature-dependent extension of n-type inversion regions in
HgCdTe photodiodes at low temperatures (87 K) compared to inversion regions at room
temperature (300 K). Laser-beam-induced-current (LBIC) measurement techniques are used
to obtain the photosensitive area extensions of n-type inversion in HgCdTe photodiodes for
typical n+-on-p HgCdTe photovoltaic IR detectors. The effect of temperature on the extension
of n-type conversion region is investigated by considering the sign of the LBIC signal.
Theoretical results show that the hole concentration decreases in multi-doped HgCdTe as the
temperature decreases. Consequently hole concentration is much lower than electron
concentration at 87 K. It is demonstrated that the n-type inversion region extension is caused
with the p-to-n type conversion.
The current-voltage and photo-response characteristics of middle wavelength infrared
(MWIR) HgCdTe photodiodes have been performed based on a self-consistent solution of the
Poisson's equation, the electron/hole continuity equations, and three
generation-recombination processes as Auger, Shockley-Read-Hall and optical generation
recombination. Three different carrier density approximations, (1) parabolic conduction band
approximation, (2) Bebb's non-parabolic expression, and (3) Harman's non-parabolic
approximation, are proposed to simulate the I-V curve and photo-response of MWIR HgCdTe
photovoltaic devices by considering the carrier degeneracy and the non-parabolic conduction
band. It is found that omitting non-parabolic effect can lead to an enormous deviation in the
simulation result, especially for heavily doped HgCdTe devices. Based on the calculated
results of photo-response, the parabolic conduction band and Harman's non-parabolic
approximation can lead to the response peak shift to short and long wavelength, respectively.
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.