MBE‐grown ZnO film on sapphire substrate with double buffer layers

Wang, Xinqiang; Iwaki, Hiroyuki; Ishitani, Yoshihiro; Yoshikawa, Akihiko

doi:10.1002/pssc.200304157

Cited by 5 publications

(8 citation statements)

References 12 publications

(10 reference statements)

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“…Furthermore, we adopted a GaN buffer/intermediate layer on the nitridated sapphire to further improve the quality of ZnO epilayers [8]. It was clear that the polarity of both thin AlN formed by the nitridation of the sapphire and also successively grown GaN buffer/intermediate layers were -c polarity, i.e., N-polarity [8].…”

Section: Introductionmentioning

confidence: 99%

Polarity control of ZnO films grown with high temperature N‐polar GaN intermediate layers by plasma‐assisted molecular beam epitaxy

Roh

Tomita

Ohsugi

et al. 2004

Physica Status Solidi (b)

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ZnO epilayers were grown on nitridated c-Al 2 O 3 substrates by plasma-assisted molecular beam epitaxy and the effect of the deposition temperature for GaN buffer and/or intermediate layers on the polarity of ZnO epilayer was investigated. First, it was found that the polarity of the ZnO epilayers grown on low temperature-grown GaN buffer and/or intermediate layers was uncertain and it became often +c polarity, i.e., Zn-polarity. This seems strange because the polarity of the GaN-underlying layer was -c polarity, i.e., N-polarity, and then the polarity of the under layer was not kept unchanged by the following epilayer. On the other hand, when the growth temperature of the GaN buffer/intermediate layer was increased above 850 °C, it was found that the polarity of the GaN layer was followed by the ZnO epilayers; the polarity became -c polarity, i.e., O-polarity. This reason was estimated by the effect of surface oxides on GaN which were formed just before the deposition of ZnO buffer layer on it.

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Section: Introductionmentioning

confidence: 99%

Polarity control of ZnO films grown with high temperature N‐polar GaN intermediate layers by plasma‐assisted molecular beam epitaxy

Roh

Tomita

Ohsugi

et al. 2004

Physica Status Solidi (b)

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Section: Introductionmentioning

confidence: 99%

“…At present, rf -plasma-assisted molecular beam epitaxial (rf -MBE) is applied successfully to the crystal growth of ZnO film on sapphire (0001) substrate [5]. The growth temperature of ZnO film on sapphire(0001) substrate is usually about 650 • C. It was shown that the in-plane alignment between ZnO and the sapphire were grown [1010]ZnO//[1120]sapphire by rf -MBE [5]. And this inplane alignment between ZnO and the sapphire is also shown by electron cyclotron resonance-assisted molecular beam epitaxy [2] and the first-principles calculation [3].…”

Section: Introductionmentioning

confidence: 99%

Theoretical investigation on the structural properties of ZnO grown on sapphire

Fujiwara

Ishii

Ebisuzaki³

et al. 2006

e-J. Surf. Sci. Nanotechnol.

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We have investigated the growth mechanisms of ZnO on the c-plane sapphire(0001) substrates by the firstprinciples calculation. The first-principles total energy calculations of a sapphire slab with an isolated zinc adatom and an isolated oxygen adatom explain the experimental results such that the in-plane alignment between the ZnO and the sapphire is [1010]ZnO//[1120] sapphire. Moreover, from the experimental and theoretical results of GaN/sapphire growth mechanisms, the change of the polarity is very important for the migration barrier energy. The relative total energies for the isolated zinc adatom on the sapphire(0001) surface is very small while that for the isolated oxygen adatom on the sapphire(0001) surface is very large. When analogizing these relative energies with the experimental and theoretical results of GaN/sapphire growth mechanisms, we expect that the polarity of grown ZnO film on the sapphire substrate is the O-polarity. And the polarity of the direct growth of ZnO on the sapphire (0001) substrate does not change from the O-polarity under any growth conditions without using the low-temperature amorphous ZnO buffer layer.

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“…However, due to the lack of low-cost lattice-matched-epitaxy substrate, the majority of ZnO thin films and devices have to be grown mostly on sapphire or SiC substrate in hetero-epitaxial regime. Many efforts have been made previously to achieve good ZnO films on c-plane sapphire substrate [4][5][6][7][8][9][10][11]. Using MgO as hetero-buffers, several researchers have produced high quality ZnO epi-layers [4][5][6][7][8] because MgO can mediate the lattice mismatch of 18% between c-sapphire and ZnO to 9% between ZnO/MgO and 8% between MgO/c-sapphire.…”

Section: Introductionmentioning

confidence: 99%