Novel Gallium Complexes with Malonic Diester Anions as Molecular Precursors for the MOCVD of Ga₂O₃ Thin Films

Abstract

Five different homoleptic gallium complexes with malonic diester anions [Ga(ROCOCHOCOR) 3 ] [R = Me (1), Et (2), iPr (3), tBu (4) and SiMe 3 (5)] have been synthesised and characterised by 1 H and 13 C NMR, IR spectroscopy, electron ionisation mass spectrometry (EI-MS), and single-crystal X-ray diffraction. The thermal properties of the obtained compounds were evaluated by thermogravimetric studies to assess their suitability as precursors for the metal-organic chemical vapour deposition (MOCVD) of Ga 2 O 3 thin films. MOCVD of Ga 2 O 3 thin films was carried out starting from compound 2 in light of the promising features of this precur-

Effects of film thickness and thermal treatment on the structural and opto-electronic properties of Ga-doped ZnO films deposited by sol–gel method

“…The peak positions of Zn 2p 1/2 (BEE 1045.5 eV) and Zn 2p 3/2 (BEE 1022.4 eV) agree well with the position expected for Zn in ZnO lattice [30,31]. Regarding gallium, the Ga 2p 3/2 peak position in S3 (BE E1119.2 eV) could indicate the presence of Ga(III) in an oxide environment [32,33], but in S6 and S9 their peak signals almost disappear into the background levels. The latter indicates an increase of annealing temperature to 600°C may prevent the substitution of gallium atoms into the ZnO lattice sites, such as segregating at grain boundary areas and form nonconductive gallium oxide.…”

Solution based CVD of main group materials

“…141 Whilst gallium oxide is amorphous at lower temperatures it shows semiconducting behaviour above 450 1C and changes in resistivity depending on the concentration of various reducing gases. 137,[142][143][144] Recent developments on the AACVD of gallium oxide are described below. 137,[142][143][144] Recent developments on the AACVD of gallium oxide are described below.…”

ALD and MOCVD of Ga2O3 Thin Films Using the New Ga Precursor Dimethylgallium Isopropoxide, Me2GaOiPr

“…ALD is also important as the sizes of electronic devices become smaller. Precursors for gallium oxide thin films include Ga(hfac) 3 , [38,56] Ga(dpm) 3 , [56] Ga(acac) 3 , [48] Ga[OCH(CF 3 ) 2 ] 3 (HNMe 2 ), [39] [ [40] Ga(O i Pr) 3 , [41] GaCl 3 , [42] Me 3 Ga, [43][44][45]49] Ga 2 (NMe 2 ) 6 , [46,50] [Me 2 GaNMe 2 ], [51,52] Ga(ROCOCHOCOR) 3 , [47] Et 3 Ga, [53] [Me 2 GaOCH 2 CH 2 NMe 2 ] 2 , 57 etc. Except for the trialkylgallium compounds, the precursors are mostly solids at room temperature and not convenient to use, although some of them readily volatilize with mild heating.…”

“…[36] Ga-doped zinc oxide (ZnO:Ga, GZO) is a wellknown n-type TCO material. [37] Thin films of gallium oxide have been prepared by various methods: (radiofrequency) magnetron sputter deposition, [1][2][3][4]6,7,9,10,12,25,27] electron beam evaporation, [15][16][17]21] pulsed laser deposition, [26,28,30,33,34,36] laser ablation, [31] CVD, [38][39][40][41][42][43][44][45][46][47] ALD, [48][49][50][51][52] molecular beam epitaxy, [32,35] vapor phase epitaxy, [53] spray pyrolysis, [54,55] and sol-gel process. [5,13,23,24] Among these methods, CVD is considered very important because it can readily be employed in industrial processes.…”