Anisotropic luminescence and third-order electric susceptibility of Mg-doped gallium oxide under the half-bandgap edge

Abstract

Strong anisotropy of photoluminescence of a (100)-cut β-Ga2O3 and a Mg-doped β-Ga2O3 single crystals was found in UV and visible spectral range, the bands of which were attributed to different types of transitions in the samples. Green photoluminescence in the Mg-doped sample was enhanced approximately twice. A remarkable enhancement of two-photon absorption and self-focusing in β-Ga2O3 after doping was revealed by 340-fs laser Z-scanning at 515 nm. The absolute value of complex third order susceptibility χ(3) determined from the study increases by 19 times in [001] lattice direction. Saturable absorption and associated self-defocusing were found in the undoped crystal in the [010] direction, which was explained by the anisotropic excitation of F-centers on intrinsic oxygen defects. This effect falls out of resonance in the Mg-doped crystal. The χ(3) values which are provided by a decrease of bandgap in Mg-doped β-Ga2O3 are χ(3) [001] = 1.85·10−12 esu and χ(3) [010]=χ(3) yyyy = 0.92·10−12 esu. Our result is only one order of magnitude lower than the best characteristic in green demonstrated by a Mg-doped GaN, which encourages subsequent development of Mg-doped β-Ga2O3 as an effective nonlinear optical material in this region.

A novel high performance photodetection based on axial NiO/β-Ga2O3 p-n junction heterostructure nanowires array

“…This peak at 372 nm can be ascribed to the exciton-exciton scattering corresponding to the NiO material [43]. Both the peaks at 340 nm (3.64 eV) and 330 nm (3.75 eV) can be ascribed due to the near band emission (NBE) for β-Ga 2 O 3 material in case of HS TF and axial HS NW respectively [44]. A blue shift of 10 nm is observed in axial NiO/β-Ga 2 O 3 HS NW NBE as compared to NiO/β-Ga 2 O 3 HS TF which can be ascribed to the quantum confinement effect as already observed from absorption analysis [45].…”

Multi-pixels gallium oxide UV detector array and optoelectronic applications

“…Meanwhile, its excellent thermal stability and ultra-high theoretical critical breakdown field strength (∼8 MV•cm −1 ) make it have potentials in the fields of devices including gas sensors [12][13][14], solar-blind photodetector, power devices [15][16][17][18][19] and so on. The more detailed characteristics of Ga 2 O 3 have been studied and reported in reference [20][21][22][23][24][25][26][27][28][29][30].…”

Effect of extended defects on photoluminescence of gallium oxide and aluminum gallium oxide epitaxial films

“…As such, in β-Ga 2 O 3 with strong electron phonon coupling, there is little chance of being able to spectroscopically discern different types of defects from luminescence as any defect considered can result in a very wide luminescence band, even near 0 Kelvin. This has resulted in an intense debate in defining the defects and phenomenological explanations of electronic processes that cause these particular emissions 5 – 24 . Provided in the Supplementary Information is a comprehensive review of the literature.…”