Crystal growth of a MnS buffer layer for non-polar AlN on Si (100) deposited by radio frequency magnetron sputtering

Abstract

The growth conditions of MnS thin film on a Si (100) substrate deposited by the RF-magnetron sputtering method were investigated. The MnS is a buffer layer for the epitaxial growth of non-polar AlN thin film on the Si (100) substrate. The 4°-off-Si (100) substrate and the insertion of MnS film grown at room temperature (RT-MnS) improved the crystallinity and the surface roughness of the MnS film. In particular, the 20 nm thick RT-MnS showed a reduction of surface roughness of the MnS layer deposited at 550 °C. The root mean square value of the MnS layer was 0.23 nm, which is in the same range as that of the Si substrate. X-ray photoelectron spectroscopy measurements revealed that RT-MnS insertion with a thickness over 10 nm reduced the sulfur vacancy formation in the MnS film deposited on RT-MnS, and the MnS was thermally stable at the growth temperature of AlN.

Effects of Zn x Mn1−x S buffer layer on nonpolar AlN growth on Si (100) substrate

“…Our previous report revealed that the use of 4°-off-Si improves the crystallinity of MnS films. 24) 4°-off-Si was treated with HF solution after cleaning with an organic solvent and pure water. First, an initial 20 nm Zn x Mn 1−x S or MnS layer was deposited by radio frequency (RF) magnetron sputtering using MnS and ZnS sintered ceramic targets (Kojundo Chemical Laboratory, 2N and 4N grades, respectively) on 4°-off-Si at room temperature (hereafter, RT-Zn x Mn 1−x S and RT-MnS), because, according to our previous report, RT-MnS improved the crystallinity of MnS (100) films.…”

“…First, an initial 20 nm Zn x Mn 1−x S or MnS layer was deposited by radio frequency (RF) magnetron sputtering using MnS and ZnS sintered ceramic targets (Kojundo Chemical Laboratory, 2N and 4N grades, respectively) on 4°-off-Si at room temperature (hereafter, RT-Zn x Mn 1−x S and RT-MnS), because, according to our previous report, RT-MnS improved the crystallinity of MnS (100) films. 24) The base pressure was 4.1 × 10 -6 Pa, and the Ar gas pressure and RF sputtering power were set to 2.0 Pa and 150 W, respectively. On these films, 30 nm composition-spread Zn x Mn 1−x S films were deposited at 550 °C.…”

“…17) To solve these issues, we have proposed nonpolar AlN film growth on a Si (100) substrate by inserting a MnS buffer layer as a template substrate for nonpolar GaN growth. [18][19][20][21][22][23][24][25][26] In terms of the lattice mismatch, the lattice constant of the a-axis of MnS (5.22 Å) is close to that of Si and 3 times that of the a-axis of AlN. In our previous study, a nonpolar AlN film on a Si (100) substrate with a MnS buffer layer was achieved by pulsed laser deposition.…”

“…[18][19][20][21][22][23] In order to realize nonpolar GaN growth on a large-diameter Si (100) substrate, we started to fabricate AlN/MnS/Si (100) structures by sputtering. 24) However, film growth of nonpolar AlN could not be achieved by sputtering owing to the instability of the MnS/Si and MnS/AlN interfaces. MnS has a much larger thermal expansion coefficient (16.3 × 10 -6 K −1 ) than Si (2.63 × 10 -6 K −1 ) and AlN (5.27 × 10 -6 K −1 ), resulting in the degradation of the interfaces.…”

Formation of various-axis-oriented wurtzite nuclei and enlargement of the a-axis-oriented region in AlFeN films deposited on Si(100) substrates

“…[21][22][23] These films were deposited on SiO 2 glass substrates via spontaneous nucleation, which is one of the characteristics of sputtering. Recently, sputtering was used to obtain non-polar m-axis-oriented AlN films on a Si(100) substrate with a MnS buffer layer 24 and nonpolar a-axis-oriented AlN films on an r-plane sapphire substrate, 25 both of which exhibited epitaxial growth regimes. The successful fabrication of these films proves the potential of the sputtering technique for promoting epitaxial growth to construct devices comprising non-polar AlN-based layers.…”