Single phase nanocrystalline GaMnN thin films with high Mn content

Abstract

Ga 1 − x Mn x N thin films with a Mn content as high as x=0.18 have been grown using ion-assisted deposition and a combination of Rutherford backscattering spectroscopy and nuclear reaction analysis was used to determine their composition. The structure of the films was determined from x-ray diffraction, transmission electron microscopy, and extended x-ray absorption fine structure (EXAFS). The films are comprised of nanocrystals of random stacked GaMnN and there is no evidence of Mn-rich secondary phases or clusters. EXAFS measurements at the Mn and Ga edge are almost identical to those at the Ga edge from Mn-free nanocrystalline GaN films, showing that the Mn occupies the Ga lattice sites, and simulated radial distribution functions of possible Mn-rich impurity phases bear no resemblance to the experimental data. The results indicate that these are the most heavily Mn-doped single phase GaN films studied to date.

Nearest-neighbor Mn antiferromagnetic exchange inGa1−xMnxN

“…In previous work we reported that the Mn ions show an extended x-ray absorption fine structure pattern that establishes they have a coordination that is identical to that of the Ga in these and in Mn-free GaN. 30 They have four N nearest neighbors and 12 cation second-nearest neighbors. We see no evidence at all for secondary phases such as rocksalt-structure MnN, which is an antiferromagnetic metal with T N = 400°C.…”

“…29 Both the composition and structure of these films have been carefully examined. 30 The compositional details were determined by a combination of Rutherford backscattering spectroscopy, nuclear reaction analysis, and secondary-ion mass spectroscopy, with the results summarized in Table I. The surface of the films is partially oxidized, resulting in the few percent O content that is detected in some samples.…”

“…Our magnetic measurements were performed on polycrystalline films prepared by ion-assisted deposition, 29,30 showing a Mn bonding configuration that rigorously substitutes for Ga. Thus the Mn ions are bonded to four N ions in a local tetrahedral coordination, with a second ionic shell of 12 cations; the Mn ions are then found in an environment that follows that of Ga ions in GaN.…”

Structural and vibrational analysis of nanocrystalline Ga1−xMnxN films deposited by reactive magnetron sputtering

“…The success of the preparation of ferromagnetic Ga 1−x Mn x N using the molecular beam epitaxy ͑MBE͒ technique is quite recent [3][4][5][6][7] and has attracted the attention of several groups concerning the mentioned as well as other techniques. [8][9][10][11][12][13][14] In a recent report we have described the preparation of Ga 1−x Mn x N nanocrystalline films using the sputtering technique. 15 The low substrate temperature, allowed by the plasma breaking of N 2 molecules and the use a metallic Ga target covered by small Mn pieces, makes the preparation and Mn incorporation simple and versatile.…”

Influence of Si co-doping on magnetic, electrical and optical properties of Ga1–x Mn x N film grown by MOCVD

“…Especially for the excellent application prospect of Ga 1−x Mn x N, there has been a strong research effort on it. Different Mn ions existence forms in the host GaN lattice and the corresponding ferromagnetic induction mechanism [9][10][11][12][13][14] were reported with different growth methods [15][16][17][18][19][20]. Despite many investigations, the origin and control of ferromagnetism in Ga 1−x Mn x N are, arguably, the most controversial research topics in material science and condensed-matter physics today and there is still much work to do in fabrication and characterization of relevant materials.…”