Investigation of N2 plasma GaAs surface passivation efficiency against air exposure: towards an enhanced diode

Emerging two-dimensional gallium chalcogenides, such as gallium telluride (GaTe), are considered promising layered semiconductors that can serve as vital building blocks towards the implementation of nanodevices in the fields of nanoelectronics, optoelectronics, and quantum photonics. However, oxidation-induced electronic, structural, and optical changes observed in ambient-exposed gallium chalcogenides need to be further investigated and addressed. Herein, we report on the thickness-dependent effect of air exposure on the Raman and photoluminescence (PL) properties of GaTe flakes, with thicknesses spanning in the range of a few layers to 100 nm. We have developed a novel chemical passivation that results in complete encapsulation of the as-exfoliated GaTe flakes in ultrathin hydrogen–silsesquioxane (HSQ) film. A combination of correlation and comparison of Raman and PL studies reveal that the HSQ-capped GaTe flakes are effectively protected from oxidation in air ambient over the studied-period of one year, and thus, preserving their structural and optical characteristics. This contrasts with the behavior of uncapped GaTe, where we observe a significant reduction of the GaTe-related PL (~100×) and Raman (~4×) peak intensities for the few-layered flakes over a period of few days. The time-evolution of the Raman spectra in uncapped GaTe is accompanied by the appearance of two new prominent broad peaks at ~130 cm−1 and ~146 cm−1, which are attributed to the formation of polycrystalline tellurium, due to oxidation of ambient-exposed GaTe. Furthermore, and by leveraging this novel passivation, we were able to explore the optical anisotropy of HSQ-capped GaTe flakes. This is caused by the one-dimensional-like nature of the GaTe layer, as the layer comprises Ga–Ga chains extending along the b-axis direction. In concurrence with high-resolution transmission electron microscopy analysis, polarization-dependent PL spectroscopy was used to identify the b-axis crystal direction in HSQ-capped GaTe flakes with various thicknesses over a range of wavelengths (458 nm–633 nm). Thus, our novel surface-passivation offers a new approach to explore and reveal the physical properties of the layered GaTe, with the potential of fabricating reliable polarization-dependent nanophotonics with structural and optical stability.

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GaAs Surface Passivation for Device Applications.

10.21236/ada116843 ◽

1982 ◽

Author(s):

C. L. Anderson ◽

M. D. Clark

Keyword(s):

Surface Passivation ◽

Gaas Surface ◽

Device Applications

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GaAs(100) Surface Passivation with Sulfide and Fluoride Ions

MRS Advances ◽

10.1557/adv.2017.380 ◽

2017 ◽

Vol 2 (51) ◽

pp. 2915-2920

Author(s):

Pawan Tyagi

Keyword(s):

Surface Passivation ◽

Single Step ◽

Gaas Surface ◽

Surface Recombination Velocity ◽

Double Step ◽

Fluoride Ions ◽

Rutherford Back Scattering ◽

Near Surface ◽

Photoluminescence Study ◽

Sulfide Ions

ABSTRACTInteraction of GaAs with sulfur can be immensely beneficial in reducing the deleterious effect of surface states on recombination attributes. Bonding of sulfur on GaAs is also important for developing novel molecular devices and sensors, where a molecular channel can be connected to GaAs surface via thiol functional group. 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.

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Photoreflectance study of the role of a thin AlOx layer in a GaAs surface passivation and the Schottky barrier forming

The Ninth International Conference on Advanced Semiconductor Devices and Mircosystems ◽

10.1109/asdam.2012.6418525 ◽

2012 ◽

Author(s):

M. Kucera ◽

R. Kudela ◽

J. Novak

Keyword(s):

Schottky Barrier ◽

Surface Passivation ◽

Gaas Surface

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A comparison of the effectiveness of GaAs surface passivation with sodium and ammonium sulfide solutions

Physics of the Solid State ◽

10.1134/1.1129831 ◽

1997 ◽

Vol 39 (1) ◽

pp. 54-57 ◽

Cited By ~ 12

Author(s):

V. N. Bessolov ◽

E. V. Konenkova ◽

M. V. Lebedev

Keyword(s):

Surface Passivation ◽

Gaas Surface ◽

Ammonium Sulfide

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GaAs Surface Passivation by InGaP Thin Film

MRS Proceedings ◽

10.1557/proc-240-777 ◽

1991 ◽

Vol 240 ◽

Cited By ~ 1

Author(s):

Fumiaki Hyuga ◽

Tatsuo Aoki ◽

Suehiro Sugitani ◽

Kazuyoshi Asai ◽

Yoshihiro Imamura

Keyword(s):

Thin Film ◽

Thin Films ◽

Carrier Concentration ◽

High Performance ◽

Surface Passivation ◽

Wide Bandgap ◽

Gaas Surface ◽

Photoluminescence Intensity ◽

Barrier Heights ◽

Wide Bandgap Materials

ABSTRACTInGaP thin films are evaluated as wide-bandgap materials for GaAs surface passivation. A 200-Å InGaP thin film increases GaAs photoluminescence intensity 25-fold and enables Schottky barrier heights of more than 0.6 eV on n-type GaAs layers with a carrier concentration of 3×1018 /cm3. These effects persist after annealing at 800 °C for 10 min. InGaP thin films are thus suitable as surface passivation films for high-performance GaAs-MESFETs.

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