Polarity, Morphology and Reactivity of Epitaxial GaN Films on Al2O3(0001)

Starke, U.; Sloboshanin, S.; Tautz, F. Stefan; Seubert, A.; Schaefer, J. A.

doi:10.1002/(sici)1521-396x(200001)177:1<5::aid-pssa5>3.0.co;2-k

Cited by 15 publications

(16 citation statements)

References 13 publications

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“…These variations are attributed to the difference in surface structure of Àc polarity material. For example, the oxygen incorporation is expected to be higher at the Àc polar surface [13], and the adsorption of hydrogen showed a selective reactivity, preferring the N site [14]. Therefore, we ascribe the different etching characteristics for the Àc and c polar surfaces to differences in the surface bonding states.…”

Section: Resultsmentioning

confidence: 99%

Characteristics of the GaN Polar Surface during an Etching Process in KOH Solution

Sumiya

Yoshimura

et al. 2000

phys. stat. sol. (a)

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The etching characteristics of GaN films prepared by several different methods were investigated. The polarity of all the GaN samples was first determined by coaxial impact collision ion scattering spectroscopy (CAICISS). From the relationship between the etching characteristics and the polarity it is confirmed that selective etching in KOH solution is consistent with the polarity rather than either the deposition method or the surface morphology. These etching characteristics are related to the polarity of the surface.Introduction Wurtzite-structure GaN, which exhibits polarity along the c-axis, has been used intensively for blue and green optoelectronic devices and high speed or power electronics applications [1 to 3]. Since the polarity of GaN has a great effect on the growth [4] and the device performance [5,6], determination of the polarity is one of the most important factors to consider. We have investigated the determination of GaN polarity using coaxial impact collision ion scattering spectroscopy (CAICISS) [7]. This analysis technique was found to be reliable for determining the polarity of the material. However, this polarity detection method is complicated, as is the conversion beam electron diffraction technique (CBED) [8,9]. Therefore, a simple method of determining the polarity has been required. Recently, it was found that an aqueous solution of KOH selectively attacks one polarity of a GaN surface grown by either metalorganic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE), whereas surfaces of the opposite polarity remain completely unaffected, even by a long term dip in this chemical reagent [10,11]. Generally, GaN films deposited by MOCVD and MBE have Ga-face (c) and N-face (Àc) polarity, respectively [12]. Therefore, it is likely that etching in KOH solution can be used as a simple method for determining the polarity. However, it is still unclear if the difference in etching is only caused by the polarity difference, and the universality of this method is still uncertain when applied to GaN films deposited by other methods. Moreover, the nature of selective etching by alkali solution is also in need of further investigation.In this report, GaN films were prepared by several different growth techniques. The relationship between the etching characteristics and the polarity determined by

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Section: Resultsmentioning

confidence: 99%

Characteristics of the GaN Polar Surface during an Etching Process in KOH Solution

Sumiya

Yoshimura

et al. 2000

phys. stat. sol. (a)

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“…Significant different behavior from the devices with their own surface atomic configurations is observed. The nitrogen atom on the GaN surface has stronger affinity to hydrogen atom than gallium [12][13][14], The semipolar GaN diode also shows the large response to hydrogen, though its surface atomic configuration is Ga polar [15,16]. Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Time dependence of current changes in the semipolar(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) sensor as a function of cycling the ambient from N 2 to 4% H 2 in N 2 .…”

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confidence: 99%

(Invited) Hydrogen Sensing Characteristics of Gallium Nitrides with Various Crystal Planes

Kim

Baik²,

Ren

et al. 2014

ECS Trans.

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We investigated hydrogen sensing characteristics of semipolar (11-22) GaN Schottky diode, and compared to various crystal planes of GaN including conventional gallium polar c-plane (0001), nitrogen polar c-plane (000-1), and a-plane (11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The semipolar GaN diode showed remarkable current change to 4% hydrogen in nitrogen and the device exhibited full recovery into original current level under nitrogen ambient. Each plane has its own surface configuration and shows different hydrogen responsivity. In case of (11-22) plane GaN, its current response to hydrogen is very large even though its surface is terminated with gallium atoms, since active nitrogens position beneath the gallium atoms.

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“…Since there are different reactivities for the N-face and Ga-faces (Starke et al, 2000;Mayumi et al, 2001;Northrup and Neugebauer, 2004), it is interesting to note how these different surfaces react with different chemicals. The polarity determined by the GaN surface has been used to improve the performance of AlGaN/GaN HEMTs (Ambacher et al, 1999).…”

Section: 19mentioning

confidence: 99%

“…However, the density functional theory suggests that hydrogen has a much higher affi nity for the N-face surface of GaN than the Ga-face (Northrup and Neugebauer, 2004). High resolution electron energy loss spectroscopy (HREELS) showed a strong preference of N-sites for the adsorption of hydrogen gas or atomic H (Starke et al, 2000). It was also shown that, below 820, N-polar GaN has a much faster reaction rate than that of the Ga-polar GaN surface (Mayumi et al, 2001).…”

Section: 19mentioning

confidence: 99%