Pulsed Laser Deposition of Doped Lanthanum Gallate and In Situ Analysis by Mass Spectrometry of the Laser Ablation Plume

Abstract

Sr- and Mg-doped LaGaO3 powders with various dopant concentrations (La1 - x Sr x Ga1 - y Mg y O3 - ( x + y )/2 where 0.02 ≤ x ≤ 0.2 and 0.02 ≤ y ≤ 0.2) were synthesized through a novel solution combustion route. X-ray diffraction patterns indicate orthorhombic structure for compositions 0 ≤ x ≤ 0.075 and 0 ≤ y ≤ 0.075 and primitive − cubic for 0.1 ≤ x ≤ 0.2 and 0.1 ≤ y ≤ 0.2. Thin films of La1 - x Sr x Ga1 - y Mg y O3 - ( x + y )/2 (0.1 ≤ x ≤ 0.2 and 0.1 ≤ y ≤ 0.2) were deposited using both Nd:YAG (532 nm) and excimer (248 nm) lasers. The as-deposited films at room temperature were amorphous, which on annealing at 973 K exhibited single-phase cubic structure. Films deposited with excimer laser were smooth and particulate free compared to Nd:YAG laser deposition. The LSGM films on Si[111] and sapphire[0001] substrates showed good surface morphology compared to films on MgO[001] and amorphous quartz. Films were found to be slightly rich in Sr/La ratio compared to target composition. O+, O, Ga+, Ga, and La+ were the major species in the laser ablation plume with ion and neutral velocities of 3 × 105 and 3 × 104 cm/s, respectively.

Structural studies of Sr- and Mg-doped LaGaO3

“…Various crystal structures, i.e., monoclinic, orthorhombic, and cubic, have been reported. LaGaO 3 exhibits a perovskite structure with orthorhombic symmetry [1][2][3][4][5][6][7][8][9][10]. There is clearly no uniformity in the literature about the crystal structure of LSGM.…”

Laser ablation of La0.9Sr0.1Ga0·8Mg0.2O2.85 — plume and film characterization

“…Single phase LSGMO for use as target is prepared by the decomposition of corresponding metal nitrates -urea complexes followed by calcining at 1350 ~ as reported in the literature [7]. In this method, a concentrated solution of urea in water is added with constant stirring, to a saturated aqueous solution of La, St, Ga and Mg nitrate.…”

Langmuir probe measurements and mass spectrometry of plasma plumes generated by laser ablation of La0.4Ca0.6MnO3

“…[1][2][3] The evaporated plasma plume contains ionized atoms and molecules, neutrals and electrons, and the kinetics of the plasma plume will have a direct influence on the structural and physical properties of a deposited film. To better understand these plasma properties, a range of plasma analytical techniques such as Langmuir probe, 4-10 plasma imaging, [11][12][13][14] emission spectroscopy, [15][16][17][18][19][20] and mass spectrometry [21][22][23][24][25][26] have been used also in a number of combinations to cover different aspects and properties of plasma species. 27,28 For example, Geohegan and Puretzky investigated the laser ablation plume thermalization dynamics in background gases thereby combining optical absorption and emission spectroscopy, imaging and ion probe analysis.…”

“…Mass spectroscopy may be used to distinguish different ion masses and charge. In previous studies, both quadrupole 21,25 and time-of-fight mass spectrometers [22][23][24] have been used to determine the ionic composition of the plume. Since Langmuir probe analysis and mass spectrometry have different advantages and limitations, it is of interest to explore what can be learned by using a combination of the two techniques, and to determine the extent to which the two measurements can be reconciled.…”