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The effect of Ga/In ratio and annealing temperature on the nonlinear absorption behaviors in amorphous TlGaxIn(1-x)S2 (0 ≤ x ≤ 1) chalcogenide thin films
Optics & Laser Technology ( IF 4.6 ) Pub Date : 2020-03-31 , DOI: 10.1016/j.optlastec.2020.106230
Bekir Asilcan Ünlü , Ahmet Karatay , Mustafa Yüksek , Hüseyin Ünver , Nizami Gasanly , Ayhan Elmali

The amorphous semiconductor TlGaxIn(1-x)S2 (0 ≤ x ≤ 1) chalcogenide thin films were prepared with 70 nm thicknesses by using vacuum evaporation technique. The nonlinear absorption properties of the films were studied by Z-scan technique. The energy band gap values were calculated by using linear absorption spectra. The effect of Ga/In ratio leads to increase 0.22 eV in band gap energy. To derive the transmission in open aperture Z-scan data, a theoretical model incorporating two photon and free carrier absorptions and their saturations were considered and effective nonlinear absorption coefficients and saturation intensity thresholds extracted from the fitting of the experimental results. Highest effective nonlinear absorption coefficient was found for TlInS2 sample due to having the smallest energy bandgap. In an attempt to investigate the effect of localized defect states on the nonlinear absorption, TlGaS2 thin films were annealed up to 473 K. It was found that increasing annealing temperature leads to reduction of the localized defect states. Nonlinear absorption coefficient and saturation intensity threshold decrease with reduction of the localized defect states.



中文翻译:

Ga / In比和退火温度对无定形TlGa x In (1-x) S 2(0≤x≤1)硫族化物薄膜中非线性吸收行为的影响

使用真空蒸发技术制备了厚度为70 nm的非晶半导体TlGa x In (1-x) S 2(0≤x≤1)硫族化物薄膜。通过Z扫描技术研究了薄膜的非线性吸收特性。通过使用线性吸收光谱来计算能带隙值。Ga / In比的影响导致带隙能量增加0.22eV。为了得出开孔Z扫描数据的透射率,考虑了一个包含两个光子和自由载流子吸收及其饱和度的理论模型,并从实验结果的拟合中提取了有效的非线性吸收系数和饱和强度阈值。发现TlInS的最高有效非线性吸收系数2个样本,因为它们的能带隙最小。为了研究局部缺陷状态对非线性吸收的影响,将TlGaS 2薄膜退火至473K。发现提高退火温度会降低局部缺陷状态。非线性吸收系数和饱和强度阈值随着局部缺陷状态的减小而减小。

更新日期:2020-03-31
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