Comparison of GaMnN epilayers prepared by ion implantation and metalorganic chemical vapor deposition

Abstract

The ferromagnetic semiconductor GaMnN has been produced by two methods – ion implantation and metalorganic chemical vapor deposition (MOCVD). P‐type, n‐type, and intrinsic GaN layers grown by MOCVD were ion‐implanted with 3 × 1016/cm2 Mn+ at 200 keV and subsequently annealed under various conditions. Considerable lattice damage is observed by analyzing the peak asymmetry in X‐ray diffraction; annealing only partially recovers this damage. Second phases (MnxNy, GaxMny and Mn4–xGaxN1–y) have been detected upon subsequent annealing. Epitaxial GaMnN layers have been fabricated by MOCVD using Cp2Mn as the manganese precursor. These films were specular and exhibited an increasing dark reddish‐brown tinge with increasing Mn‐concentration and thickness, consistent with GaMnN grown by other methods. X‐ray diffraction revealed symmetric peaks with almost identical lattice parameters to undoped GaN, and no macroscopic second phase formation. Magnetic hysteresis is observed in the ion implanted as well as in MOCVD‐grown films at room temperature. Stronger magnetization was present in the implanted p‐type films and unannealed MOCVD‐grown films, providing evidence that Fermi level control is important for the magnetic properties of these materials. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Impact of Manganese incorporation on the structural and magnetic properties of MOCVD-grown Ga1−xMnxN

“…This second phase is not observed in the samples capped with a thin GaN layer, even at annealing temperatures of 900 o C, though further investigations are required to determine the post-annealing phase purity of the capped samples. The Mn 6 N 2.58 and Mn 3 N 2 phases were not observed via XRD in the annealed MOCVD-grown samples as had been previously reported in implanted samples [13].…”

“…As many of the initial results for Ga 1-x Mn x N were of implanted material [9,10], there would always be some post processing required when using this technique. Excessive annealing was also found to produce second phases in as-grown and implanted material, though the exact phase produced varied from Mn 3 N 2 and Mn 6 N 2.58 [11] to GaMn intermetallics [12] to Mn 3 GaN [13,14] depending on the processing conditions. Ultimately, the optimal growth and processing path for room temperature ferromagnetic GaMnN must be understood.…”

Multifunctional III-nitride dilute magnetic semiconductor epilayers and nanostructures as a future platform for spintronic devices

“…This second phase is not observed in the samples capped with a thin GaN layer, even at annealing temperatures of 900 o C, though further investigations are required to determine the post-annealing phase purity of the capped samples. The Mn 6 N 2.58 and Mn 3 N 2 phases were not observed via XRD in the annealed MOCVD grown samples as has been previously reported in implanted samples [16].…”

“…As many of the initial results for Ga 1-x Mn x N were of implanted material, there would always be some post processing required from this technique. Excessive annealing was also found to produce second phases in as-grown and implanted material, though the exact phase produced varied from Mn 3 N 2 and Mn 6 N 2.58 [34] to GaMn intermetallics [35] to Mn 3 GaN [16,24] depending on the processing conditions. Ultimately, the optimal growth and processing path for room temperature ferromagnetic Ga 1-x Mn x N must be understood for future applications.…”

“…Experimental efforts have successfully grown Ga 1-x Mn x N which has exhibited room temperature ferromagnetism by a number of different means, including bulk crystal growth [12][13][14], ion implantation [15][16][17][18][19][20][21], postgrowth diffusion [22], and molecular-beam epitaxy [23][24][25][26]. It is unclear at this point whether the ferromagnetic behavior is due to the homogeneous behavior of the alloy, or rather due to ferromagnetic nanoclusters.…”