Reduction of Recombination Velocity on GaAs Surface by Ga‐S and As‐S Bond‐Related Surface States from  (  NH 4 ) 2 S  x Treatment

1997 ◽  
Vol 144 (6) ◽  
pp. 2106-2115 ◽  
Author(s):  
H. Sik ◽  
Y. Feurprier ◽  
C. Cardinaud ◽  
G. Turban ◽  
A. Scavennec
Keyword(s):  
Surface States ◽  
Gaas Surface ◽  
Recombination Velocity

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

2005 ◽  
Vol 891 ◽  
Author(s):  
Zhimei Zhu ◽  
Elena Plis ◽  
Abdenour Amtout ◽  
Pallab Bhattacharya ◽  
Sanjay Krishna
Keyword(s):  
Infrared Detectors ◽  
Surface Passivation ◽  
Surface Recombination ◽  
Surface States ◽  
Depletion Region ◽  
Surface Recombination Velocity ◽  
Diode Array ◽  
Ammonium Sulfide ◽  
Picosecond Excitation ◽  
Recombination Velocity

ABSTRACTThe 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.

GaAs surface states observed by x‐ray photoemission

1979 ◽  
Vol 16 (5) ◽  
pp. 1300-1301 ◽  
Author(s):  
R. Ludeke ◽  
L. Ley
Keyword(s):  
Surface States ◽  
Gaas Surface ◽  
X Ray

Deep level transient spectroscopy study of GaAs surface states treated with inorganic sulfides

1988 ◽  
Vol 53 (12) ◽  
pp. 1059-1061 ◽  
Author(s):  
D. Liu ◽  
T. Zhang ◽  
R. A. LaRue ◽  
J. S. Harris ◽  
T. W. Sigmon
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Surface States ◽  
Gaas Surface ◽  
Spectroscopy Study ◽  
Transient Spectroscopy

scholarly journals Sulfide and Fluoride Ions Based Passivation of GaAs(100) Surface and Concept of Combining Surface Passivation with Tunnel Junction Based Molecular Devices

2019 ◽  
Author(s):  
Pawan Tyagi
Keyword(s):  
Surface Passivation ◽  
Surface States ◽  
Single Step ◽  
Gaas Surface ◽  
Double Step ◽  
Fluoride Ions ◽  
Rutherford Back Scattering ◽  
Near Surface ◽  
Photoluminescence Study ◽  
Sulfide Ions

Sulfur interaction with GaAs can reduce the harmful effect of surface states on recombination attributes. Apart from surface passivation, study of sulfur bonding on GaAs is also important for developing novel molecular electronics and molecular spintronics devices, where a molecular channel can be connected to at least one GaAs surface via thiol functional group. Excess thiol functional groups that are not involved in making molecular device channels can serve as the passivants to quench surface states. However, the primary challenge lies in increasing the stability and effectiveness of the sulfur passivated GaAs. We have investigated the effect of single and double step surface passivation of n-GaAs(100) by using the sulfide and fluoride ions. Our single-step passivation involved the use of sulfide and fluoride ions individually. However, the two kinds of double-step passivations were performed by treating the n-GaAs surface. In the first approach GaAs surface was firstly treated with sulfide ions and secondly with fluoride ions, respectively. In the second double step approach GaAs surface was first treated with fluoride ions followed by sulfide ions, respectively. Sulfidation was conducted using the nonaqueous solution of sodium sulfide salt. Whereas the passivation steps with fluoride ion was performed with the aqueous solution of ammonium fluoride. Both sulfidation and fluoridation steps were performed either by dipping the GaAs sample in the desired ionic solution or electrochemically. Photoluminescence was conducted to characterize the relative changes in surface recombination velocity due to the single and double step surface passivation. Photoluminescence study showed that the double-step chemical treatment where GaAs was first treated with fluoride ions followed by the sulfide ions yielded the highest improvement. The time vs. photoluminescence study showed that this double-step passivation exhibited lower degradation rate as compared to widely discussed sulfide ion passivated GaAs surface. We also conducted surface elemental analysis using Rutherford Back Scattering to decipher the near surface chemical changes due to the four passivation methodologies we adopted. The double-step passivations affected the shallower region near GaAs surface as compared to the single step passivations.

Electrochemical Sulfur Treatments of GaAs Using Na2S and (NH4)2S Solutions: A Surface Chemical Study

1992 ◽  
Vol 282 ◽  
Author(s):  
J. Yota ◽  
V. A. Burrows
Keyword(s):  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Surface Film ◽  
Surface Recombination ◽  
Chemical Study ◽  
Lower Surface ◽  
State Density ◽  
Gaas Surface ◽  
Surface Recombination Velocity ◽  
Recombination Velocity

ABSTRACTChemical sulfur treatments of GaAs have been shown to improve the GaAs surface electronic properties. These treatments result in lower surface state density, lower surface recombination velocity, and shifting or unpinning of the Fermi level, in addition to improvement in the performance of devices. However, there is still considerable controversy regarding the chemical nature of the surface film which results from this chemical sulfidation. It has been shown that this film is not stable chemically and electronically. The improved surface electronic properties decay with time and are sensitive to the chemical environment of the material. In this study, using surface infrared reflection spectroscopy (SIRS) and x-ray photoelectron spectroscopy (XPS), we have investigated the electrochemical sulfidation of GaAs as a possible new method to produce a GaAs surface that is stable chemically and electronically. We have found that anodic treatments with Na2S and (NH4S solutions result in the removal of the pre-existing oxide of GaAs and the formation of films comprising sulfur, sodium carbonate, ammonium thiosulfate, and sulfide and sulfur-oxygen compounds of arsenic. Rinsing the GaAs with water removes the bulk of the film, leaving behind a surface on which only arsenic sulfide was detected.

Reduction of GaAs surface recombination velocity by chemical treatment

1980 ◽  
Vol 36 (1) ◽  
pp. 76-79 ◽  
Author(s):  
R. J. Nelson ◽  
J. S. Williams ◽  
H. J. Leamy ◽  
B. Miller ◽  
H. C. Casey ◽  
...  
Keyword(s):  
Chemical Treatment ◽  
Surface Recombination ◽  
Gaas Surface ◽  
Surface Recombination Velocity ◽  
Recombination Velocity

Photoemission study of surface states of the (110) GaAs surface

1976 ◽  
Vol 13 (2) ◽  
pp. 725-738 ◽  
Author(s):  
Paul E. Gregory ◽  
W. E. Spicer
Keyword(s):  
Surface States ◽  
Gaas Surface ◽  
Photoemission Study

Zero-loss omega-filtered REM and RHEED on the new Zeiss 912

1991 ◽  
Vol 49 ◽  
pp. 616-617
Author(s):  
J.C.H. Spence ◽  
J. Mayer
Keyword(s):  
Electron Microscopy ◽  
Materials Science ◽  
Surface States ◽  
Ccd Camera ◽  
Dark Field ◽  
Ion Pump ◽  
Magnetic Imaging ◽  
Reflection Electron Microscopy ◽  
Diffraction Patterns ◽  
Large Background

The Zeiss 912 is a new fully digital, side-entry, 120 Kv TEM/STEM instrument for materials science, fitted with an omega magnetic imaging energy filter. Pumping is by turbopump and ion pump. The magnetic imaging filter allows energy-filtered images or diffraction patterns to be recorded without scanning using efficient parallel (area) detection. The energy loss intensity distribution may also be displayed on the screen, and recorded by scanning it over the PMT supplied. If a CCD camera is fitted and suitable new software developed, “parallel ELS” recording results. For large fields of view, filtered images can be recorded much more efficiently than by Scanning Reflection Electron Microscopy, and the large background of inelastic scattering removed. We have therefore evaluated the 912 for REM and RHEED applications. Causes of streaking and resonance in RHEED patterns are being studied, and a more quantitative analysis of CBRED patterns may be possible. Dark field band-gap REM imaging of surface states may also be possible.

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