aln buffer
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2022 ◽  
Vol 141 ◽  
pp. 106423
Author(s):  
Yangfeng Li ◽  
Xiaotao Hu ◽  
Yimeng Song ◽  
Zhaole Su ◽  
Haiqiang Jia ◽  
...  

Coatings ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 94
Author(s):  
Pepen Arifin ◽  
Heri Sutanto ◽  
Sugianto ◽  
Agus Subagio

We report the growth of non-polar GaN and AlGaN films on Si(111) substrates by plasma-assisted metal-organic chemical vapor deposition (PA-MOCVD). Low-temperature growth of GaN or AlN was used as a buffer layer to overcome the lattice mismatch and thermal expansion coefficient between GaN and Si(111) and GaN’s poor wetting on Si(111). As grown, the buffer layer is amorphous, and it crystalizes during annealing to the growth temperature and then serves as a template for the growth of GaN or AlGaN. We used scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) characterization to investigate the influence of the buffer layer on crystal structure, orientation, and the morphology of GaN. We found that the GaN buffer layer is superior to the AlN buffer layer. The thickness of the GaN buffer layer played a critical role in the crystal quality and plane orientation and in reducing the cracks during the growth of GaN/Si(111) layers. The optimum GaN buffer layer thickness is around 50 nm, and by using the optimized GaN buffer layer, we investigated the growth of AlGaN with varying Al compositions. The morphology of the AlGaN films is flat and homogenous, with less than 1 nm surface roughness, and has preferred orientation in a-axis.


2022 ◽  
Vol 120 (1) ◽  
pp. 012102
Author(s):  
Ki-Sik Im ◽  
Uiho Choi ◽  
Minho Kim ◽  
Jinseok Choi ◽  
Hyun-Seop Kim ◽  
...  

2021 ◽  
pp. 1-1
Author(s):  
Tuğçe ATAŞER ◽  
Durmuş DEMİR ◽  
Ahmet Kursat BILGILI ◽  
Mustafa ÖZTÜRK ◽  
Süleyman ÖZÇELİK

2021 ◽  
Vol 2086 (1) ◽  
pp. 012037
Author(s):  
K Yu Shubina ◽  
D V Mokhov ◽  
T N Berezovskaya ◽  
E V Pirogov ◽  
A V Nashchekin ◽  
...  

Abstract In this work, the AlN/Si(111) epitaxial structures grown consistently by plasma assisted molecular beam epitaxy (PA MBE) and hydride vapour phase epitaxy (HVPE) methods were studied. The PA MBE AlN buffer layers were synthesized via coalescence overgrowth of self-catalyzed AlN nanocolumns on Si(111) substrates and were used as templates for further HVPE growth of thick AlN layer. It was shown that described approaches can be used to obtain AlN layers with sufficiently smooth morphology. It was found that HVPE AlN inherited crystallographic polarity of the AlN layer grown by PA MBE. It was demonstrated that the etching of such AlN/Si(111) epitaxial structures results in partial separation of the AlN epilayers from the Si(111) substrate and allows to form suspended structures. Moreover, the avoidance of surface damage and backside overetching was achieved by use thin Cr film as surface protective coating and by increasing the layer thickness accordingly.


Author(s):  
Libin Zhang ◽  
Rongjun Zhang ◽  
Bo Yang ◽  
Sheng Liu ◽  
Zhiyin Gan
Keyword(s):  

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1063
Author(s):  
Badis Riah ◽  
Julien Camus ◽  
Abdelhak Ayad ◽  
Mohammad Rammal ◽  
Raouia Zernadji ◽  
...  

This paper reports the effect of Silicon substrate orientation and Aluminum nitride buffer layer deposited by molecular beam epitaxy on the growth of aluminum nitride thin films deposited by a DC magnetron sputtering technique at low temperatures. The structural analysis has revealed a strong (0001) fiber texture for both Si(100) and (111) substrates, and a hetero-epitaxial growth on a AlN buffer layer, which is only a few nanometers in size, grown by MBE onthe Si(111) substrate. SEM images and XRD characterization have shown an enhancement in AlN crystallinity. Raman spectroscopy indicated that the AlN film was relaxed when it deposited on Si(111), in compression on Si(100) and under tension on a AlN buffer layer grown by MBE/Si(111) substrates, respectively. The interface between Si(111) and AlN grown by MBE is abrupt and well defined, contrary to the interface between AlN deposited using PVD and AlN grown by MBE. Nevertheless, AlN hetero-epitaxial growth was obtained at a low temperature (<250 °C).


2021 ◽  
pp. 2141013
Author(s):  
Hsin Che Lee ◽  
Cheng-Che Lee ◽  
Hsin Jung Lee ◽  
Wei Yu Lee ◽  
Wei Ching Chuang

In the present study, AlGaN/GaN high-electron-mobility transistors (HEMTs) were fabricated through metal–organic chemical vapor deposition. Gate recess etching, combined with inductively coupled plasma reactive ion etching, was adopted, and etching time was controlled to manipulate the threshold voltage [Formula: see text]. The DC characteristics of devices etched for 0–25 s were investigated. [Formula: see text] exhibited a 1.9-V positive shift in the device with the AlGaN layer etched for 25 s. The effect of an AlN buffer layer on the [Formula: see text] shift was also investigated. The [Formula: see text] of the HEMT etched for 25 s and without an AlN buffer layer exhibited a positive shift of 3.1 V.


2021 ◽  
pp. 2141010
Author(s):  
Cheng Che Lee ◽  
Hsin Jung Lee ◽  
Hsin Che Lee ◽  
Wei Yu Lee ◽  
Wei Ching Chuang

In this paper, AlGaN/GaN HEMTs with an AlN buffer layer were fabricated. Analyses on the crystal quality of the GaN epitaxial layer by Raman spectroscopy have been purposed. By introducing an AlN layer on sapphire substrate, the maximum drain current of the HEMT increased from 481 mA/mm to 522 mA/mm at [Formula: see text] V. Subthreshold slope was reduced from 638.3 mV/decade to 240.9 mV/decade and the electron mobility increased from 1109 cm2 V[Formula: see text]s[Formula: see text] to 1781 cm2 V[Formula: see text]s[Formula: see text]. These results showed that using an AlN buffer layer can improve the crystal quality of the GaN epitaxial layer, thus optimize the device performances of the GaN-based HEMTs.


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