X-ray photoelectron spectroscopy and x-ray diffraction study of the thermal oxide on gallium nitride

Wolter, Scott D.; Luther, B. P.; Waltemyer, D. L.; Önneby, C.; Mohney, Suzanne E.; Molnar, R. J.

doi:10.1063/1.118944

Cited by 236 publications

(161 citation statements)

References 22 publications

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“…From XPS data, Ga 2p 3/2 , Ga 2p 1/2 , and N 1 s core level peak positions were obtained at 1118.2, 1144.8, and 399.4 eV, respectively. These results well agree with the literature (Wolter et al 1997;Pal et al 2003) confirming the presence of GaN nanomaterials.…”

Section: Resultssupporting

confidence: 83%

Synthesis of blue-shifted luminescent colloidal GaN nanocrystals through femtosecond pulsed laser ablation in organic solution

et al. 2016

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We demonstrate the synthesis of GaN nanocrystals (NCs) with the sizes of less than the doubled exciton Bohr radius leading quantum confinement effects via a single-step technique. The generation of colloidal GaN nanoparticles (NPs) in organic solution through nanosecond (ns) and femtosecond (fs) pulsed laser ablation (PLA) of GaN powder was carried out. Ns PLA in ethanol and polymer matrix resulted in amorphous GaN-NPs with the size distribution of 12.4 ± 7.0 and 6.4 ± 2.3 nm, respectively, whereas fs PLA in ethanol produced colloidal GaN-NCs with spherical shape within 4.2 ± 1.9 nm particle size distribution. XRD and selected area electron diffraction analysis of the product via fs PLA revealed that GaN-NCs are in wurtzite structure. Moreover, X-ray photoelectron spectroscopy measurements also confirm the presence of GaN nanomaterials. The colloidal GaN-NCs solution exhibits strong blue shift in the absorption spectrum compared to that of the GaN-NPs via ns PLA in ethanol. Furthermore, the photoluminescence emission behavior of fs PLA-generated GaN-NCs in the 295-400 nm wavelength range is observed with a peak position located at 305 nm showing a strong blue shift with respect to the bulk GaN.

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Section: Resultssupporting

confidence: 83%

Synthesis of blue-shifted luminescent colloidal GaN nanocrystals through femtosecond pulsed laser ablation in organic solution

et al. 2016

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“…Wolter et al determined that Ga 3d states in Ga 2 O 3 have a chemical shift of +1.2 eV on GaN. 39 Surdu-Bob et al 40 determined the Ga 3d chemical shift of gallium suboxide Ga 2 O relative to Ga 2 O 3 of −0.6 eV. Therefore, it is estimated that Ga 2 O has a chemical shift of +0.6 eV relative to bulk GaN.…”

Section: Figmentioning

confidence: 99%

Preparation of gallium nitride surfaces for atomic layer deposition of aluminum oxide

Kerr

Chagarov

et al. 2014

The Journal of Chemical Physics

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A combined wet and dry cleaning process for GaN(0001) has been investigated with XPS and DFT-MD modeling to determine the molecular-level mechanisms for cleaning and the subsequent nucleation of gate oxide atomic layer deposition (ALD). In situ XPS studies show that for the wet sulfur treatment on GaN(0001), sulfur desorbs at room temperature in vacuum prior to gate oxide deposition. Angle resolved depth profiling XPS post-ALD deposition shows that the a-Al 2 O 3 gate oxide bonds directly to the GaN substrate leaving both the gallium surface atoms and the oxide interfacial atoms with XPS chemical shifts consistent with bulk-like charge. These results are in agreement with DFT calculations that predict the oxide/GaN(0001) interface will have bulk-like charges and a low density of band gap states. This passivation is consistent with the oxide restoring the surface gallium atoms to tetrahedral bonding by eliminating the gallium empty dangling bonds on bulk terminated GaN(0001).

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“…3a) suggests presence of three components at 1116.8, 1118.1 and 1119.7 eV respectively, corresponding to Ga-N bonds related peaks, the last peak is possibly Ga-oxyfluoride (GaOF x ) related, the latter coming from the etch process. 23,24 The Ga-N related peak is relatively weaker due to the chemically etched surface. This fitted average Ga-N related peak and the normal peak for Ga-O are a little off from their usual position, possibly due to the presence of the oxyfluoride component at the surface (Table II).…”

Section: Resultsmentioning

confidence: 99%

“…The XPS peak assignment was based on accepted standard literature reports. [15][16][17][18][19][20][21][22][23][24][25][26] GaP was used as a standard sample to understand the GaN XPS peaks better, since in Ga based compound semiconductor samples, very often there is interference of Ga related XPS and Auger peaks with other elemental peaks over a wide binding energy (BE) range. …”

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confidence: 99%

Wet Etching and Surface Analysis of Chemically Treated InGaN Films

Karar¹,

Opila²,

Beebe

2011

J. Electrochem. Soc.

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This paper discusses the performance of different wet chemical etchants on InGaN. It is shown that certain etchants can be used to chemically etch and remove appreciable amounts of InGaN even though the etch rate is not as high as observed for other III-V materials. The performance of etchants studied here were (i) two different ratios of HF, HNO 3 , (ii) cyclic usage of NH 4 OH followed by HCl, (iii) hot H 2 SO 4 and H 3 PO 4 mixture, and (iv) conc. NH 4 OH. The etched surfaces have then been analyzed by x-ray photoelectron spectroscopy (XPS). Different etch residues were observed on the top surface. These results suggest an alternative to reactive plasma etching or photo-enhanced electrochemical etching of InGaN type materials. Based on the observed performance of the etchants studied, it was also possible to segregate the surface cleaning protocols and etchants. It is well known that in semiconductor materials and device fabrication, the important issues are materials' purity, growth, defect control, lithography, etching, contact formation, and device performance.1,2 Among these, etching is an important process in which the grown material is required to be partially removed using specific patterns for subsequent doping, metalization, device structure formation, etc. In such processes, the rate of material removal has to be fast and repeatable. There is another associated process, in which the top layer of a material is cleaned before subsequent growth by removing a few angstroms and associated top layer contaminants. In this cleaning process, it is essential that the top layers are removed with care and the least amount of material is wasted. Thus, this chemical cleaning process has to be one with a slow material removal rate and with the least amount of interfering residues.Such etching and cleaning may be done by electrochemical, wet chemical methods, reactive ion or sputter ion cleaning.3 Electrochemical processes are not always very selective while removing materials and often require very tight control over bias voltages and currents. Wet chemical etching is a method of removing the top layer of a material in a solvent leading to its dissolution in the reaction medium. Often the etchants are a combination of acids or a combination of bases. In wet chemical methods, with proper calibration, it is possible to retain better material crystalline quality of the etched material and by controlling the concentration of chemicals in the reaction, the material removal rate can also be rigorously controlled. However in all etch steps, residues from etching steps are present; these need to be understood to evaluate the likely effects on the subsequent electrical properties of the device created. Wet chemical etching is thus often the preferred etching mechanism for lithographic process. It has often been seen that the traditional wet chemical or electrochemical processes may also have their other limitations, even though they are quite cost effective. Inability to get high etching rates or reaction induced surface p...

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X-ray photoelectron spectroscopy and x-ray diffraction study of the thermal oxide on gallium nitride

Cited by 236 publications

References 22 publications

Synthesis of blue-shifted luminescent colloidal GaN nanocrystals through femtosecond pulsed laser ablation in organic solution

Synthesis of blue-shifted luminescent colloidal GaN nanocrystals through femtosecond pulsed laser ablation in organic solution

Preparation of gallium nitride surfaces for atomic layer deposition of aluminum oxide

Wet Etching and Surface Analysis of Chemically Treated InGaN Films

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