Lattice damage assessment and optical waveguide properties in LaAlO₃single crystal irradiated with swift Si ions

Abstract

As one of the representative ABO 3 perovskite-structured oxides, lanthanum aluminate (LaAlO 3 ) crystal has emerged as one of the most valuable functional-materials, and has attracted plenty of fundamental research and promising applications in recent years. Electronic, magnetic, optical and other properties of LaAlO 3 strongly depend on its crystal structure, which could be strongly modified owing to the nuclear or electronic energy loss deposited in an ion irradiation environment and, therefore, significantly affecting the performance of LaAlO 3 -based devices. In this work, utilizing swift (tens of MeV) Si-ion irradiation, the damage behavior of LaAlO 3 crystal induced by nuclear or electronic energy loss has been studied in detail utilizing complementary characterization techniques. Differing from other perovskite-structured crystals in which the electronic energy loss could lead to the formation of an amorphous region based on the thermal spike mechanism, in this case, intense electronic energy loss in LaAlO 3 will not induce any obvious structural damage. The effects of ion irradiation on the mechanical properties, including hardness increase and elastic modulus decrease, have been confirmed. On the other hand, considering the potential applications of LaAlO 3 in the field of integrated optoelectronics, the optical-waveguide properties of the irradiation region have been studied. The significant correspondence (symmetrical inversion) between the iWKB-reconstructed refractive-index profile and SRIM-simulated dpa profile further proves the effects (irradiation-damage production and refractive-index decrease) of nuclear energy loss during the swift-ion penetration process in LaAlO 3 crystal. In the case of the rather-thick damage layer produced by swift-ion irradiation, obtaining a damage profile will be constrained owing to the analysis-depth limitation of the characterization techniques (RBS/channeling), and our analysis process (optical guided-mode measurement and subsequent refractive-index-profile reconstruction) also provides a new approach to study the damage behavior (damage profile) once the functional relationship between the refractive index and lattice disorder for the specific material could be determined.

Swift heavy ion tracks in alkali tantalate crystals: a combined experimental and computational study

“…The properties in such nanoscale regions containing lattice disorder or an amorphous phase are drastically changed and modified compared with the surrounding virgin bulk. Thus, swift heavy ion irradiation is a powerful technique that is utilized to study the undesirable phenomena (creep, swelling, embrittlement, etc) occurring in irradiation environments [12][13][14][15][16] but also has beneficial applications in material modification and device fabrication on the nano-and micrometer scales [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Alkali tantalate crystals (KTaO 3 , LiTaO 3 , etc) with perovskite-like structures exhibit versatile properties that are attractive for numerous applications, such as electro-optic waveguides in microelectronics [32], pyroelectrics in neutron generation [33] and photocatalysts in pollutant degradation [34] and water splitting [35].…”

Latent tracks and novel infrared waveguide formation in lithium tantalate irradiated with swift heavy ions

“…Over the past several decades, energetic (MeV)-ion irradiation has been considered a useful tool for tailoring novel structures and relevant properties of solid materials as well as a powerful technique for studying the damage effects and performance degradation of functional materials in radiation environments [1][2][3][4][5][6][7][8][9][10][11][12][13]. During the ion-irradiation process, an energetic ion loses energy primarily via two processes: nuclear energy loss (S n ) that originates from the elastic collisions between moving ions and target nuclei and electronic energy loss (S e ) that originates from the inelastic collisions between moving ions and target electrons [14].…”

First-principles calculations and Raman scattering evidence for local symmetry lowering in rhombohedral ilmenite: temperature- and pressure-dependent studies

“…There is no doubt that ABX 3 perovskites are a key material for developing new devices for several applications, covering the fields of gas sensors [1], detectors [2], solar cells [3], actuators [4], capacitors [5], microwave resonators [6], ferroelectric random access memory [7], superconductors [8], waveguides [9], catalysts [10], and so on [11][12][13][14]. Such practical uses are possible due to their ability to accommodate very different atoms at both A-and B-sites that generates complex systems with tunable physical properties [10].…”