Direct evidence of tensile strain in wurtzite structuren−GaNlayers grown onn−Si(111)using AlN buffer layers

The effect of the AlxGa1−xN/AIN buffer layer on the properties of GaN/Si(111) film grown by NH3-MBE

“…If stress coefficient of 4.3 cm À1[18][19][20] is adopted, the increased tensile stress is as much as 230 MPa for sample B and 630 MPa for sample C, respectively.…”

Growth of GaN film on Si (111) substrate using AlN sandwich structure as buffer

“…We adopt here the value reported by Gleize et al [20] for the AlN stress coefficient (3.39 cm À 1 /GPa for the E 2 -high mode of AlN) and the value reported by Bairamov et al [15] for the GaN stress coefficient (4.3 cm À 1 /GPa for the E 2 -high mode of GaN). The calculated stresses in the top GaN layer of samples A and B are the same at 0.23 GPa, which is basically in accordance with the literature [21] as the residual tensile stress, and sample C's calculated stress is 0.6 GPa.…”

“…4 shows the Raman scattering spectra of the three samples at room temperature. It shows that the strongest peak at about 525 cm À 1 and the weakest peak at 619 cm À 1 [15] are from the Si substrate. Consistent with literature reports, both the E 2 -high and A 1 -LO modes of GaN are observed.…”

Phase control of GaN on Si by nanoscale faceting in metalorganic vapor-phase epitaxy

“…7, two peaks near 550 and 565 cm À1 are observed from the former while a single peak at 564 cm À1 appears in the latter one. The peaks near 564 and 565 cm À1 represent the high-frequency E 2 mode of hexagonal-phase GaN and the peak near 550 cm À1 is close to the TO mode of cubic-phase GaN on GaAs(0 0 1) [19][20][21][22]. Thus, the absence of a TO mode in the GaN on wide-area Si(1 1 1) suggests that the dominant phase of GaN on wide-area Si(1 1 1) is hexagonal, confirming the PL results of Fig.…”