1063-7397/02/3106- $27.00 © 2002 MAIK “Nauka /Interperiodica”
Russian Microelectronics, Vol. 31, No. 6, 2002, pp. 351–358. Translated from Mikroelektronika, Vol. 31, No. 6, 2002, pp. 414–422.
Original Russian Text Copyright © 2002 by Vasilyev, Golenkov, Dvoretsky, Esaev, Zakhar’yash, Klimenko, Kozlov, Marchishin, Ovsyuk, Reva, Sidorov, Sizov, Suslyakov, Talipov.
Modern IR detectors are mostly based on
Te solid solutions. Varying
, one can adjust
the detector to wavelengths from 1 to over 20
devices operate at temperatures ranging from the liq-
uid-nitrogen to room temperature. They can be fabri-
cated by LPE, MOCVD, or MBE. The third process has
tangible advantages. It enables one to grow epitaxial
layers with prescribed properties because analytical
methods can be employed for the
both process parameters and HgCdTe-layer properties
[1, 2]. More importantly, creating a suitable depth pro-
ﬁle of the Cd fraction, MBE makes it possible to pro-
duce heteroepitaxial layers with expanded forbidden
bands near the surface and the HgCdTe–buffer inter-
face. This will suppress surface recombination and,
hence, greatly reduce surface stray currents. Figure 1
gives a typical example of a depth proﬁle for
Te on GaAs, a combination used in both sin-
gle detectors and arrays. Moreover, this approach
allows one to raise the operating temperature of an
array to over 200 K.
On the other hand, Hg
Te becomes less and
less resistant to mechanical stress with decreasing
(and, hence, energy gap) or increasing temperature.
Accordingly, the pressure exerted on the HgCdTe sur-
face must be kept below a certain level in order to avoid
the formation of electrically active structural imperfec-
tions in the material and the degradation of the n–p
junctions. This consideration should be borne in mind
when devising methods for assembling hybrid arrays.
Below, we report a technology of making 128
288 ﬂip-chip hybrid IR detector arrays and sin-
gle IR detectors. The arrays consist of photodiodes with
low series impedances, and the single detectors are
photoconductivity cells. All the detectors are built
around an MBE-grown HgCdTe heteroepitaxial layer.
We describe silicon multiplexers employed and present
some performance data on detectors that are operated in
the wavelength range 3–5 or 8–12
m and at 78–80 or
Figure 2 illustrates the main process steps for the
photodiode arrays. One of major problems in producing
the devices is the passivation of the HgCdTe surface.
The coat must meet the following stringent require-
(1) It must be synthesized at a temperature not
higher than 100
(2) It must have a surface ﬁxed-charge density less
(3) It must show good adhesion and retain the prop-
erty after any possible process step.
(4) It must endure any possible thermal treatment
and must display stable performance under ﬁeld condi-
These requirements are basically satisﬁed by SiO
deposited at 100
C. However, the material is known to
react with air water vapor, so that a positive charge of
may accumulate in the bulk of the coat in a
few weeks. For this reason, the SiO
coat is capped with
a silicon nitride layer (by CVD at 60
The photodiodes are based on p-type HgCdTe, with
the n–p junctions created by boron ion implantation .
This generates n-type radiation defects in speciﬁed
regions of the HgCdTe layer. As a rule, no implant
annealing is performed.
Mid- and Long-Wave IR Detectors Using
Te Heteroepitaxial Layer
V. V. Vasilyev*, A. G. Golenkov**, S. A. Dvoretsky*, D. G. Esaev*,
T. I. Zakhar’yash*, A. G. Klimenko*, A. I. Kozlov*, I. V. Marchishin*, V. N. Ovsyuk*,
V. P. Reva**, Yu. G. Sidorov*, F. F. Sizov**, A. O. Suslyakov*, and N. Kh. Talipov*
* Institute of Semiconductor Physics, Siberian Division, Russian Academy of Sciences, Novosibirsk, Russia
** Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received February 26, 2002
—A complete production technology is developed for single-cell and array IR detectors using an
Te heteroepitaxial layer. The array detectors implement a bump-bonded ﬂip-chip hybrid
architecture. The arrays are constructed in photodiodes and have a size of 128
128 or 4
288. The single-cell
detectors are built around a photoconductivity cell. The detectors are operated in the wavelength range 3–5 or
m and at 78–80 or 200–220 K. Some performance data on the detectors are presented.