Improved interfacial properties of thermal atomic layer deposited AlN on GaN

Kim, Hogyoung; Kim, Nam Do; An, Sang Chul; Yoon, Hee Ju; Choi, Byung Joon

doi:10.1016/j.vacuum.2018.10.067

Cited by 23 publications

(15 citation statements)

References 17 publications

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“…3(a) has confirmed the presence of additional compound, peak b can be associated with the presence of this additional compound. The BEs of Al2p observed here were within the reported BE for Al 3+ (Supplementary 2(a)) and the BEs of N1s were also consistent with the reported BE for N 3− in AlN (Supplementary 2(b)) [26][27][28] . However, the spectra of Al2p and N1s did not exhibit significant changes upon introduction of Si, except for a slight shift in BE of Al2p and N1s when Si addition is high (19 at.%).…”

Section: Effect Of Si Addition As Single Dopant On the Crystal Structsupporting

confidence: 91%

“…7(a)) suggested the presence of an additional compound (*), these additional doublets are believed to correspond with the presence of this additional compound. However, changes in Mg to Si ratio does not seem to significantly affect the BEs of Al2p and N1s, since they are in close agreement with the observed BE for Al 3+ in AlN (Supplementary 6(a)) [26][27][28] and for N 3in AlN, respectively (Supplementary 6(b)) [26][27][28] . However, the width of N1s spectra is slightly affected by Mg/Si ratio, which might be correlate with the presence of multiple nitride compounds in the thin films, as have been also indicated by Mg2p and Si2p spectra.…”

Section: Elucidation On Mechanism Of Polarity Inversion -Effect Of Sisupporting

confidence: 78%

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Polarity Inversion of Aluminum Nitride Thin Films by using Si and MgSi Dopants

Anggraini

Uehara

Hirata

et al. 2020

Sci Rep

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polarity is among the critical characteristics that could governs the functionality of piezoelectric materials. In this study, the polarity of aluminum nitride (AlN) thin films was inverted from Al-polar to N-polar by doping Si into AlN in the range of 1-15 at.%. Polarity inversion from Al-polar to N-polar also occurred when MgSi was codoped into AlN with Mg to Si ratio was less than 1. However, the polarity can be reversed from N-polar to Al-polar when the ratio of Mg and Si was greater than 1. The effect of Si and MgSi addition was investigated with regards to their crystal structure, lattice parameters, polarity distribution and the oxidation state of each elements. Furthermore, the effect of intermediate layer as well as the presence of point defect (i.e. aluminum vacancy) were investigated and how these factors influence the polarity of the thin films are discussed in this report.Wurtzite structure aluminum nitride (AlN) is one of the important building blocks for various advanced electromechanical and optoelectronics devices. AlN has been touted as a promising material for radio frequency (RF) acoustic devices such as resonators, due to its high acoustic velocity, high quality (Q) factor, thermal stability and the compatibility with CMOS technology 1 . With the ever-growing market of wireless telecommunication devices, the need to continuously enhance the piezoelectric property of AlN has made it the subject of extensive study and research.Improving the piezoelectric properties of AlN can be done by either augmenting the magnitude of piezoelectric response along c-axis (d 33 ) or by controlling the polarity of the thin film. Since the non-centrosymmetry of wurtzite AlN is the origin of polarization along the c-axis, a highly c-oriented AlN thin film could exhibits either Al-or N-polarity 2 . While considerable efforts have been devoted to find the best dopants that could produce the highest enhancement in the piezoelectric response 3-5 , manipulating the polarity of AlN is equally essential in designing high performance devices, since having thin film with different polarity could lead to different electronic property and eventually alter the performance of the developed device 2,6-8 . For example, having a stack of N-polar layer on top of an Al-polar layer enabled a solidly mounted resonator BAW (SMR-BAW) to operate at higher frequency which made it capable to function in more advance telecommunication technology 2,6 .When it comes to controlling the polarity, there are numbers of efforts that have been reported to successfully switch the polarity of nitride thin films from metal-polar into N-polar or vice versa 1,8-12 . The insertion of a buffer layer or an intermediate layer is one of the common approaches that was utilized to inverse the polarity [8][9][10]13,14 . Aside from this, switching the polarity can also be done by altering the thin film deposition parameters (e.g. pressure or target power), inserting metal seed or by introducing oxygen during thin film deposition 12,15-17 . However, these metho...

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Section: Effect Of Si Addition As Single Dopant On the Crystal Structsupporting

confidence: 91%

Section: Elucidation On Mechanism Of Polarity Inversion -Effect Of Sisupporting

confidence: 78%

Polarity Inversion of Aluminum Nitride Thin Films by using Si and MgSi Dopants

Anggraini

Uehara

Hirata

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…AlGaN growth was done by the combination of GaN and AlN reactions with a pulse ratio of 1:1, corresponding to Al0.85Ga0.15N. According to the X-ray photoelectron spectroscopy (XPS) analysis, we found that the dominant peak in the Al 2p core-level spectra shifted to lower binding energy with the increase of AlN thickness due to a strong Al-Al peak, which was associated with the strain relaxation generated from the lattice mismatch between AlN and GaN [16]. In other words, when the thickness of AlN exceeded ~10 nm, the strain relaxation affected the overgrown AlN film quality.…”

Section: Methodsmentioning

confidence: 94%

Forward Current Transport Properties of AlGaN/GaN Schottky Diodes Prepared by Atomic Layer Deposition

Kim

Choi

2020

Coatings

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Atomic layer deposited AlGaN on GaN substrate with different thicknesses was prepared and the electron transport mechanism of AlGaN/GaN Schottky diodes was investigated. Above 348 K, both 5 and 10 nm thick AlGaN showed that the thermionic emission model with inhomogeneous Schottky barrier could explain the forward current transport. Analysis using a dislocation-related tunneling model showed that the current values for 10 nm thick AlGaN was matched well to the experimental data while those were not matched for 5 nm thick AlGaN. The higher density of surface (and interface) states was found for 5 nm thick AlGaN. In other words, a higher density of surface donors, as well as a thinner AlGaN layer for 5 nm thick AlGaN, enhanced the tunneling current.

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“…Distinguishing nitrogen peak on the wide-spectrum of as-deposited films is somewhat challenging, which is why it is best instead to consult the high-resolution spectra provided below. The proneness of AlN to extensive oxidation is a notorious issue reported by multiple studies [6,17,18,29]. Carbon is also an unavoidable contaminant occurring from atmosphere [6,17,30].…”

Section: X-ray Photoelectron Spectroscopy (Xps) Datamentioning

confidence: 99%

“…Al-N Al 2p 74.7 [17], 73.5 [30], 74.3 [35], 74.4 [39], 74.2 [40], 74.0 [11], 74.6 [41] N 1s 397.8 [29], 396.4 [30], 397.3 [39], 397.4 [40], 396.5 [41], 397.7 [29], 397.1 [42] Analysis of C 1s peak (Figure 9) shows the presence of different organic bonds, which are O-C=O at 2884 eV for as-deposited sample and O-C=O 287.6 eV, C-O-C 285.9 at eV for annealed sample [6,25,30]. The formation of new types of bonds is well expected when high temperature treatment is applied (Figure 9b), especially with a reactive element such as oxygen, the coalescence of the layer during extreme heating is also a promoting factor for such reactivity.…”

Section: Bond Peak Binding Energies (Ev)mentioning

confidence: 99%

Aluminum Nitride Nanofilms by Atomic Layer Deposition Using Alternative Precursors Hydrazinium Chloride and Triisobutylaluminum

et al. 2020

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The aim of this study is motivated by the pursuit to investigate the performance of new and as yet untested precursors such as hydrazinium chloride (N2H5Cl) and triisobutylaluminum Al(C4H9)3 in the AlN atomic layer deposition (ALD) process as well as to study effects of successive annealing on the quality of the resulting layer. Both precursors are significantly cheaper than their conventional counterparts while also being widely available and can boast easy handling. Furthermore, Al(C4H9)3 being a rather large molecule might promote steric hindrance and prevent formation of undesired hydrogen bonds. Chemical analysis is provided by X-ray photoelectron spectroscopy (XPS) and secondary-ion mass spectrometry (SIMS) techniques; surface morphology was studied using atomic force microscopy (AFM). Chlorine containing precursors such as AlCl3 are usually avoided in ALD process due to the risk of chamber contamination. However, experimental data of this study demonstrated that the use of N2H5Cl does not result in chlorine contamination due to the fact that temperature needed for HCl molecules to become reactive cannot be reached within the AlN ALD window (200–350 °C). No amount of chlorine was detected even by the most sensitive techniques such as SIMS, meaning it is fully removed out of the chamber during purge stages. A part of the obtained samples was subjected to annealing (1350 °C) to study effects of high-temperature processing in nitrogen atmosphere, the comparisons with unprocessed samples are provided.

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Improved interfacial properties of thermal atomic layer deposited AlN on GaN

Cited by 23 publications

References 17 publications

Polarity Inversion of Aluminum Nitride Thin Films by using Si and MgSi Dopants

Polarity Inversion of Aluminum Nitride Thin Films by using Si and MgSi Dopants

Forward Current Transport Properties of AlGaN/GaN Schottky Diodes Prepared by Atomic Layer Deposition

Aluminum Nitride Nanofilms by Atomic Layer Deposition Using Alternative Precursors Hydrazinium Chloride and Triisobutylaluminum

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