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Investigation of Surface Passivation in InAs/GaSb Strained-Layer-Superlattices Using Picosecond Excitation Correlation Measurement and Variable-Area Diode Array Surface Recombination Velocity Measurement

Published online by Cambridge University Press:  01 February 2011

Zhimei Zhu ,
Elena Plis ,
Abdenour Amtout ,
Pallab Bhattacharya  and
Sanjay Krishna
Zhimei Zhu
Affiliation:
zhimeiz@umich.edu, University of Michigan, Electrical Engineering and Computer Science, 323 SOLANO DR. SE, ALBUQUERQUE, NM, 87108, United States, (734) 262-1972, (505) 272 7801
Elena Plis
Affiliation:
alien@chtm.unm.edu, University of New Mexico, Center for High Technology Materials, United States
Abdenour Amtout
Affiliation:
amtoutab@chtm.unm.edu, University of New Mexico, Center for High Technology Materials, United States
Pallab Bhattacharya
Affiliation:
pkb@eecs.umich.edu, University of Michigan, Ann Arbor, Department of Electrical Engineering and Computer Science, United States
Sanjay Krishna
Affiliation:
skrishna@chtm.unm.edu, University of New Mexico, Center for High Technology Materials, United States
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Abstract

The effect of ammonium sulfide passivation on InAs/GaSb superlattice infrared detectors was investigated using two complementary techniques, namely, picosecond excitation correlation (PEC) measurement and variable-area diode array (VADA) surface recombination velocity (SRV) measurement. PEC measurements were conducted on etched InAs/GaSb superlattice mesas, which were passivated in aqueous ammonium sulfide solutions of various strengths for several durations. The PEC signal's decay time constant (DTC) is proportional to carrier lifetimes. At 77 K the PEC signal's DTC of the as-grown InAs/GaSb superlattice sample was 2.0 ns, while that of the unpassivated etched sample was reduced to 1.2 ns by the surface states at the mesa sidewalls. The most effective ammonium sulfide passivation process increased the PEC signal's DTC to 10.4 ns. However it is difficult to isolate surface recombination from other processes that contribute to the lifetime using the PEC data, therefore a VADA SRV measurement was undertaken to determine the effect of passivation on surface recombination. The obtained SRV in the depletion region of the InAs/GaSb superlattice and GaSb junction was 1.1×106 cm/s for the unpassivated sample and 4.6×105 cm/s for the passivated sample. At 77 K the highest R0A value measured in our passivated devices was 2540 W cm2 versus 0.22 W cm2 for the unpassivated diodes. The results of the lifetime, the SRV and the R0A measurements indicate that ammonium sulfide passivation will improve the performance of InAs/GaSb superlattice infrared detectors.

Keywords

optoelectronicpassivationsurface reaction
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 891: Symposium EE – Progress in Semiconductor Materials V – Novel Materials and Electronics and Optoelectronic Applications , 2005 , 0891-EE01-08
Copyright
Copyright © Materials Research Society 2006

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References

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