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中国物理学会期刊

Cu掺杂β-Ga2O3薄膜的制备及紫外探测性能

CSTR: 32037.14.aps.72.20230971

Preparation and ultraviolet detection performance of Cu doped β-Ga2O3 thin films

CSTR: 32037.14.aps.72.20230971
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  • β-Ga2O3作为第三代宽禁带半导体材料, 具有禁带宽度大(4.9 eV)、击穿电场强, 吸收边正好位于日盲紫外波段(波长200—280 nm)内, 且在近紫外以及整个可见光波段具有较高的透过率, 使得β-Ga2O3是一种非常适合制作日盲紫外光电探测器的材料. 目前在p型β-Ga2O3材料方面的研究还较少, 但p型β-Ga2O3材料的制备对于其光电器件的应用至关重要, 因此成功制备p型β-Ga2O3材料就显得尤为关键. 采用化学气相沉积法在蓝宝石衬底上生长出不同Cu掺杂量的β-Ga2O3薄膜, 并对薄膜的形貌、晶体结构和光电特性进行了测试. 发现随着Cu掺杂量的增加, 样品( \bar 201 )晶面的衍射峰向小角度方向发生了移动, 这说明Cu2+替代了Ga3+进入到了Ga2O3晶格中. 此外, 在Cu掺杂β-Ga2O3薄膜上蒸镀Au作为叉指电极, 制备出了金属-半导体-金属结构光电导型日盲紫外探测器, 并对其紫外探测性能进行了研究. 结果表明, 在10 V偏压、254 nm波长紫外光下, 器件的光暗电流比约为3.81×102, 器件的上升时间和下降时间分别是0.11 s和0.13 s. 此外, 在光功率密度为64 μW/cm2时, 器件的响应度和外部量子效率分别是1.72 A/W和841%.

     

    Solar-blind UV photodetectors (SBPs) have attracted great attention because they are widely used in missile tracking, fire detection, biochemical analysis, astronomical observations, space-to-space communications, etc. At present, it is found that wide bandgap semiconductor materials such as AlxGa1-xN, Mg1Zn1-xO, diamond and β-Ga2O3 are ideal semiconductor materials for developing high-performance SBPs. The ultra-wide band gap semiconductor material, β-Ga2O3, has a large band gap width of 4.9 eV, strong breakdown electric field, absorption edge located in the solar blind ultraviolet band (200–280 nm), and it also has high transmittance in the near ultraviolet and the whole visible band. Therefore, β-Ga2O3 is a very suitable material for making solar blind UV photodetectors. However, the p-type β-Ga2O3 is difficult to dope, which limits the further development of β-Ga2O3 devices. In this work, the β-Ga2O3 thin films with different Cu doping content are grown on sapphire substrates by chemical vapor deposition method, and the morphology, crystal structure and optical properties of β-Ga2O3 films are measured. The test results show that the surfaces of β-Ga2O3 films with different Cu content are relatively smooth, and the ( \bar 201 ) diffraction peak positions shift toward the lower degree side with the increase of Cu content, which indicates that Cu2+ replaces Ga3+ and enters into the β-Ga2O3 lattice. The optical absorption spectrum measurement indicates that the energy gaps of samples are evidently narrowed with the increase of Cu doping concentration. Hall measurements indicate that the Cu doped β-Ga2O3 thin films have a p-type conductivity with a hole concentration of 7.36 × 1014, 4.83 × 1015 and 1.69 × 1016 cm–3, respectively. In addition, a photoconductive UV detector with metal-semiconductor-metal structure is prepared by evaporating Au on a Cu-doped β-Ga2O3 thin film, and its UV detection performance is studied. The results show that the photocurrent value of the device increases with Cu content increasing. The photo-to-dark current ratio (Il/Id) is about 3.8×102 of 2.4% Cu content device under 254 nm-wavelength light at 10 V. The rise time and decay time are 0.11 s and 0.13 s, respectively. Furthermore, the responsivity and external quantum efficiency can reach 1.72 A/W and 841% under 254 nm-wavelength light with a light intensity of 64 μW/cm2.

     

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