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. 2024 Feb 2;14(7):4543-4555.
doi: 10.1039/d3ra07568k. eCollection 2024 Jan 31.

Influence of annealing pretreatment in different atmospheres on crystallization quality and UV photosensitivity of gallium oxide films

Wen-Jie Chen  1   2 , Hong-Ping Ma  1   2   3 , Lin Gu  1   2 , Yi Shen  1   2 , Ruo-Yun Yang  1   2 , Xi-Yuan Cao  4 , Mingyang Yang  5 , Qing-Chun Zhang  1   2   3
Affiliations

Influence of annealing pretreatment in different atmospheres on crystallization quality and UV photosensitivity of gallium oxide films

Wen-Jie Chen et al. RSC Adv. .

Abstract

Due to their high wavelength selectivity and strong anti-interference capability, solar-blind UV photodetectors hold broad and important application prospects in fields like flame detection, missile warnings, and secure communication. Research on solar-blind UV detectors for amorphous Ga2O3 is still in its early stages. The presence of intrinsic defects related to oxygen vacancies significantly affects the photodetection performance of amorphous Ga2O3 materials. This paper focuses on growing high quality amorphous Ga2O3 films on silicon substrates through atomic layer deposition. The study investigates the impact of annealing atmospheres on Ga2O3 films and designs a blind UV detector for Ga2O3. Characterization techniques including atomic force microscopy (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) are used for Ga2O3 film analysis. Ga2O3 films exhibit a clear transition from amorphous to polycrystalline after annealing, accompanied by a decrease in oxygen vacancy concentration from 21.26% to 6.54%. As a result, the response time of the annealed detector reduces from 9.32 s to 0.47 s at an external bias of 10 V. This work demonstrates that an appropriate annealing process can yield high-quality Ga2O3 films, and holds potential for advancing high-performance solar blind photodetector (SBPD) development.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1. (a)–(d) Two- and three-dimensional morphology and roughness of Ga2O3 thin films under varying annealing atmospheres: (a) unannealed, (b) Ar-annealed, (c) N2-annealed, (d) O2-annealed. (e) Grazing incident XRD patterns of Ga2O3 films prepared using different annealing atmospheres. (f) Surface roughness of Ga2O3 films prepared under diverse annealing atmospheres.
Fig. 2
Fig. 2. XPS analyses of Ga2O3 samples annealed under different atmospheres: (a) survey peaks; (b) O 1s spectra; and (c) Ga 2p spectra. The O 1s spectra of Ga2O3 films annealed in various atmospheres are shown for (d) unannealed, (e) Ar, (f) N2, and (g) O2.
Fig. 3
Fig. 3. (a) Raman spectra of Ga2O3 annealed under different atmospheric conditions. (b) Ultraviolet light transmittance and optical band gap of Ga2O3 annealed in different atmospheres. (c) PL spectra of Ga2O3 films under various annealing conditions. (d) Magnified PL spectral image within the wavelength range of 330–360 nm.
Fig. 4
Fig. 4. Dynamic IV-T results at different bias voltages: (a) unannealed, (b) Ar, (c) N2, and (d) O2. The (e) τ increases and (f) τ decays for Ga2O3 detectors in different annealing atmospheres (the illustrations in (e) and (f) are the schematic diagram of the detector structure and the image of the interdigital electrode, respectively).
Fig. 5
Fig. 5. I–V characteristic curves of Ga2O3 detectors annealed under various atmospheric conditions in both dark and 254 nm illuminated states: (a) unannealed, (b) Ar-annealed, (c) N2-annealed, (d) O2-annealed.
Fig. 6
Fig. 6. (a) PL spectra of Ga2O3 films under different annealing conditions. (b) Magnified PL spectral image within the 240–280 nm wavelength range. (c) Rejection ratio for each sample. (d) Calculation results for R and D* for each sample.
Fig. 7
Fig. 7. O 1s peak obtained from Ga2O3 film to determine the bandgap. The inset shows the corresponding loss structure: (a) unannealed, (b) Ar-annealed, (c) N2-annealed, (d) O2-annealed. Valence band spectra of Ga2O3 samples under distinct annealing atmospheres: (e) unannealed, (f) Ar-annealed, (g) N2-annealed, (h) O2-annealed. (i) Band shift diagram.
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