Structural Characteristics and Photoluminescence Properties of Sputter-Deposition ZnGa2O4 Thin Films on Sapphire and Si(100) Substrates

Abstract

In this paper, we report the growth and material characteristics of ZnGa2O4 thin films on c-plane sapphire and Si(100) substrates by a radio-frequency magnetron sputtering. When deposited on sapphire, the ZnGa2O4 film showed a polycrystalline nature and a less randomly oriented, primarily with the (111), (222) and (511) planes parallel to the substrate surface. On Si(100), the ZnGa2O4 thin film was randomly oriented with (311)- and (020)-plane polycrystalline properties. Transmission electron microscopy analysis revealed that an amorphous-layer interface was formed on the Si(100) substrate and the microstructure of ZnGa2O4 became disordered. The ZnGa2O4/sapphire emitted ultraviolet photoluminescence and green emissions. The dominant optical transitions depended on the deposition temperature, oxygen and Zn contents, and nature of the substrate. The structural and optical properties of sputter-deposited ZnGa2O4 thin film on sapphire indicated that sapphire substrate is suitable for the growth of crystalline, high-quality ZnGa2O4 thin film.

Bipolar self-doping in ultra-wide bandgap spinel ZnGa2O4

“…Such an absorption band has been already reported in conducting thin films [39] without clear identification of the origin. Interestingly, other groups have observed PL emissions peaking at 340 nm in zinc gallate and this emission has been associated with Ga 3+ ions substitution into the Zn 2+ ions site [40,58]. Our results suggest however that, rather than GaZn antisites, this absorption at 360 nm (~3.4 eV) might be associated with Zn atoms having strong bond with oxygen, leading to Zn-O hybridization.…”

Zinc Gallium Oxide—A Review from Synthesis to Applications

“…PLD exhibits significant advantages, such as the stoichiometry of deposited films close to that of the target, high deposition rate, low contamination level [71], precise arrival rates of atoms for compound films, and the ability to operate in high-pressure reactive gases [77]. In fact, RF magnetron sputtering has been the most successful among the various growth techniques for wide-area applications due to its easy controllability of the growth parameters, excellent packing density [74], strong adhesion, excellent film thickness uniformity, and relatively low running cost [78]. Polycrystalline or amorphous film structures are usually obtained by the RF magnetron sputtering method, which significantly affects the optoelectronic properties of the material [74].…”

“…However, RF magnetron sputtering is an effective and low-cost method to deposit thin films that can achieve good uniformity over a large area. Wang et al investigated the structural and photoluminescence characteristics of ZnGa 2 O 4 thin films using RF magnetron sputtering on sapphire and Si(100) substrate [78]. The structural characteristics of ZnGa 2 O 4 thin films deposited on sapphire and Si(100) substrates are shown in Figure 8a,b.…”

“…Room temperature PL spectra of the ZnGa 2 O 4 films deposited on: (a) sapphire(0001) and (b) Si(100) substrates[78].…”

Assessment of large critical electric field in ultra-wide bandgap p-type spinel ZnGa2O4

“…ZnGa 2 O 4 thin films have already been grown polycrystalline on sapphire substrates by MOCVD [30], RF magnetron sputtering [31,32], pulsed laser deposition (PLD) [13], with a preferential orientation along [111] of cubic spinel and equivalent direction for Al 2 O 3 (0001). Analogously, ZnGa 2 O 4 thin films have also been grown on Si substrates by atomic layer deposition (ALD) [29], PLD [33], and RF magnetron sputtering [32].…”