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.

scholarly journals Модификация электронных свойств поверхности n-InP(100) сульфидными растворами

2021 ◽  
Vol 55 (10) ◽  
pp. 895
Author(s):  
М.В. Лебедев ◽  
Т.В. Львова ◽  
А.Н. Смирнов ◽  
В.Ю. Давыдов
Keyword(s):  
Raman Spectroscopy ◽  
Electronic Properties ◽  
Electron Density ◽  
Surface Recombination ◽  
Depletion Layer ◽  
Surface Recombination Velocity ◽  
Photoluminescence Intensity ◽  
Surface Depletion ◽  
Recombination Velocity ◽  
Sulfide Solution

Photoluminescence and Raman spectroscopy are used to study the electronic properties of n-InP(100) surfaces passivated with different sulfide solutions. Such a passivation results in the increase in photoluminescence intensity of the semiconductor evidencing for the reduction in the surface recombination velocity. The increase in the photoluminescence intensity is accompanied by the narrowing of the surface depletion layer, as well as by the increase of the electron density in the probed volume of InP. The efficiency of electronic passivation of the n-InP(100) surface depends on the composition of the sulfide solution.

Nitridation by NO Or N2O of Si-SiO2 Interfaces

1999 ◽  
Vol 567 ◽  
Author(s):  
A. P. Caricato ◽  
F. Cazzaniga ◽  
G. F. Cerofolini ◽  
B. Crivelli ◽  
M. L. Polignano ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Nature ◽  
Surface Recombination ◽  
Surface Recombination Velocity ◽  
Oxide Surface ◽  
Complementary Information ◽  
X Ray ◽  
Recombination Velocity ◽  
Foreign Species

ABSTRACTX-ray photoelectron spectroscopy (XPS) and photocurrent measurements for the determination of surface recombination velocity provide complementary information on the structure of the Si-SiO2 interface, being sensitive to the chemical nature of foreign species at the interface the former, and to intrinsic defects the latter. The comparison of the XPS N(1s) peaks determined for the Si-Si0 2 interfaces nitrided in NO or N2O ambients is useful to identify the species responsible for the broadening of the peak. In fact, nitridation by NO is mainly responsible for the formation of Si3N moieties at the silicon surface in which silicon atoms are partially oxidized; while nitridation by N2O proceeds with the oxidation of Si – Si backbonds to Si – N bonds, thus resulting in the formation of N(Si(O-)3)3 groups embedded in the oxide. Surface recombination velocity by photocurrent measurements gives evidence that nitridation in N2O is associated with an appreciable co-oxidation, while nitridation in NO is mainly associated with the passivation of interface states. Furthermore N2O and NO nitridation are responsible for different morphologies of the nitrided layers.

Sulfidation and Post-Sulfidatton Reactions on Gallium Arsenide

1992 ◽  
Vol 259 ◽  
Author(s):  
J. Yota ◽  
V. A. Burrows
Keyword(s):  
Thin Film ◽  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Surface Film ◽  
Gaas Surface ◽  
Reflection Spectroscopy ◽  
Infrared Reflection ◽  
Considerable Controversy ◽  
Infrared Reflection Spectroscopy ◽  
Sulfur Containing

ABSTRACTChemical treatment of GaAs with sulfur-containing compounds has been shown to improve GaAs surface electronic properties. There is still considerable controversy, however, regarding the chemical nature of the surface film which results from the sulfidation, and of the basis of the electronic improvement and of the decay in the improved electronic properties with time. We have investigated the surface chemistry of the chemical sulfidation treatment of GaAs with Na2S.9H2O and (NH4)2S. Using surface infrared reflection spectroscopy (SIRS) and x-ray photoelectron spectroscopy (XPS), we have studied the GaAs surface and its behavior with time after such treatments. Results show that both of these sulfidation treatments removed the chemical oxide of GaAs, leaving behind a thin film on the surface. XPS results show that the Ga-O and As-O peaks were removed after treatment and that As-S and no Ga-S peaks were formed. Infrared results show that the film deposited after Na2S.9H2O treatment slowly reacted in air to form sodium carbonate and rhombic sulfur. In addition, this film contains compounds with sulfur-oxygen bonds, which most likely were arsenic sulfate, sulfite, and thiosulfate salts. The film deposited on the (NH4)2Streated GaAs surface was identified as ammonium thiosulfate and slowly decomposed with time. Rinsing with water removed the thin film formed after either sulfidation treatment.

The Performance of Hg0.8Cd0.2Te Photodetectors by Using Photo Surface Treatment

1997 ◽  
Vol 08 (04) ◽  
pp. 703-717 ◽  
Author(s):  
Y. K. Su ◽  
C. T. Lin
Keyword(s):  
Surface Treatment ◽  
Surface Recombination ◽  
Chemical Vapor ◽  
Lower Surface ◽  
Treatment Method ◽  
Cdte Layer ◽  
Surface Recombination Velocity ◽  
Noise Power ◽  
Cdte Passivation ◽  
Recombination Velocity

The principal aim of this paper is to propose an easy, vapor phase, and reproducible photo surface treatment method to improve the device performance of the Hg0.8Cd0.2Te photoconductive detector. Experimental results, including Auger electron spectroscopy (AES), MIS leakage current, 1/f noise voltage spectrum, 1/fknee frequency, responsivity Rλ, and specific detectivity D* for stacked photo surface treatment and ZnS or CdTe passivation layers are presented. By using this method, we found that there is no accumulation of Hg in the oxide/HgCdTe interface regions. Since the photo chemical vapor native oxidation is a dry oxidation method deposited at a low temperature, it can effectively suppress the Hg enhancement and the Cd depletion effects and thus obtain a high quality interface. We also found that the photo surface treatment in combination with thermally eveporated ZnS or CdTe layer would shift the 1/fknee under 100Hz in an electrical field under 50 V/cm, reduce the noise power spectrum, and achieve a lower surface recombination velocity S of 300 cm/sec as well as a high D* of 3 × 1010 cm [Formula: see text] for blackbody radiation. It was also found that HgCdTe photoconductor passivated with stacked layers shows improved interface properties when compared to the photoconductor passivated with a single passivation layer.

Electrochemical and Chemical Sulfidation of GaAs: A Surface Chemical Study

1991 ◽  
Vol 237 ◽  
Author(s):  
J. Yota ◽  
V. A. Burrows
Keyword(s):  
Infrared Spectroscopy ◽  
Electronic Properties ◽  
Chemical Nature ◽  
Surface Film ◽  
Chemical Study ◽  
Gaas Surface ◽  
Surface Chemical ◽  
Considerable Controversy ◽  
Oxygen Group ◽  
Sulfur Containing

ABSTRACTTreatment of gallium arsenide with sulfur-containing media has been shown to improve GaAs surface electronic properties. However, there is still considerable controversy regarding the chemical nature of the surface film which results from the sulfidation, and of the basis of the electronic improvement and of the decay in the improved electronic properties with time. We have investigated the surface chemistry of the chemical sulfidation treatment of GaAs with Na2S-9H2O and the electrochemical sulfidation treatment of GaAs with Na2S-9H2O-ethylene glycol. Using surface infrared spectroscopy (SIRS), we have studied the film formed on the surface after the treatments and its behavior with time. Results show that the film on the GaAs surface contains sulfur which is often associated with oxygen, that this film slowly reacts in air to form unexpected species, e.g. sodium carbonate and sulfur-oxygen group-containing compounds, and that sulfur and oxygen are non-uniformly distributed.

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

Characterization of nitrided silicon-silicon dioxide interfaces

1999 ◽  
Vol 591 ◽  
Author(s):  
M. L. Polignano ◽  
M. Alessandri ◽  
D. Brazzelli ◽  
B. Crivelli ◽  
G. Ghidini ◽  
...  
Keyword(s):  
Surface State ◽  
Surface Recombination ◽  
State Density ◽  
Constant Current ◽  
Surface Recombination Velocity ◽  
State Reduction ◽  
Surface State Density ◽  
Recombination Velocity ◽  
Silicon Interface

ABSTRACTA newly-developed technique for the simultaneos characterization of the oxide-silicon interface properties and of bulk impurities was used for a systematic study of the nitridation process of thin oxides. This technique is based upon surface recombination velocity measurements, and does not require the formation of a capacitor structure, so it is very suitable for the characterization of as-grown interfaces.Oxides grown both in dry and in wet enviroments were considered, and nitridation processes in N2O and in NO were compared to N2 annealing processes. The effect of nitridation temperature and duration were also studied, and RTO/RTN processes were compared to conventional furnace nitridation processes.Surface recombination velocity was correlated with nitrogen concentration at the oxide-silicon interface obtained by Secondary Ion Mass Spectroscopy (SIMS) measurements. Surface recombination velocity (hence surface state density) decreases with increasing nitrogen pile-up at the oxide-silicon interface, indicating that in nitrided interfaces surface state density is limited by nitridation. NO treatments are much more effective than N2O treatments in the formation of a nitrogen-rich interface layer and, as a consequence, in surface state reduction.Surface state density was measured in fully processed wafers before and after constant current stress. After a complete device process surface states are annealed out by hydrogen passivation, however they are reactivated by the electrical stress, and surface state results after stress were compared with data of surface recombination velocity in as-processed wafers.

scholarly journals Numerical Simulation Analysis of Ag Crystallite Effects on Interface of Front Metal and Silicon in the PERC Solar Cell

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 592
Author(s):  
Myeong Sang Jeong ◽  
Yonghwan Lee ◽  
Ka-Hyun Kim ◽  
Sungjin Choi ◽  
Min Gu Kang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
High Efficiency ◽  
Open Circuit Voltage ◽  
Surface Recombination ◽  
Open Circuit ◽  
Surface Recombination Velocity ◽  
Metal Interface ◽  
Ag Crystallites ◽  
Recombination Velocity

In the fabrication of crystalline silicon solar cells, the contact properties between the front metal electrode and silicon are one of the most important parameters for achieving high-efficiency, as it is an integral element in the formation of solar cell electrodes. This entails an increase in the surface recombination velocity and a drop in the open-circuit voltage of the solar cell; hence, controlling the recombination velocity at the metal-silicon interface becomes a critical factor in the process. In this study, the distribution of Ag crystallites formed on the silicon-metal interface, the surface recombination velocity in the silicon-metal interface and the resulting changes in the performance of the Passivated Emitter and Rear Contact (PERC) solar cells were analyzed by controlling the firing temperature. The Ag crystallite distribution gradually increased corresponding to a firing temperature increase from 850 ∘C to 950 ∘C. The surface recombination velocity at the silicon-metal interface increased from 353 to 599 cm/s and the open-circuit voltage of the PERC solar cell decreased from 659.7 to 647 mV. Technology Computer-Aided Design (TCAD) simulation was used for detailed analysis on the effect of the surface recombination velocity at the silicon-metal interface on the PERC solar cell performance. Simulations showed that the increase in the distribution of Ag crystallites and surface recombination velocity at the silicon-metal interface played an important role in the decrease of open-circuit voltage of the PERC solar cell at temperatures of 850–900 ∘C, whereas the damage caused by the emitter over fire was determined as the main cause of the voltage drop at 950 ∘C. These results are expected to serve as a steppingstone for further research on improvement in the silicon-metal interface properties of silicon-based solar cells and investigation on high-efficiency solar cells.

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