Photoconductive laser spectroscopy as a method to enhance defect spectral signatures in amorphous oxide semiconductor thin-film transistors
Photoconductive laser spectroscopy as a method to enhance defect spectral signatures in amorphous oxide semiconductor thin-film transistors
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DOI：
10.1063/1.5070141
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发表时间：
2019-01-07
影响因子：
4
通讯作者：
Lynch, Stephen A.
中科院分区：
文献类型：
--
作者：
Dhara, Soumen;Niang, Kham M.;Lynch, Stephen A.
半导体薄膜中的缺陷通常会留下可用于识别它们的光学光谱特征。在这封信中，我们报道了非晶态氧化物半导体薄膜晶体管的光谱分辨光电导测量。与以前报道的使用光谱过滤宽带光源记录的光导光谱测量不同，我们使用了波长可调的皮秒激光来照射薄膜。我们从光电流测量中提取了吸收系数作为波长的函数，并表明它符合先前报道的非晶氧化物半导体薄膜的典型特征行为。然而，另外，我们在光电导谱中观察到了几个尖锐的谱峰，这可能与亚带隙缺陷有关。这些增强的峰在以前报道的光电导谱中通常是看不到的。此外，我们还表明，当薄膜被加工成晶体管时，我们可以通过改变施加的栅极偏置电压来控制测量的灵敏度。通过使用波长可调谐激光器实现的增强使其成为一种特别灵敏的表征工具，并且可以另外用于区分在器件制造之后被合并的缺陷。由AIP出版公司授权出版。
Defects in semiconductor thin-films often leave optical spectral signatures that can be used for their identification. In this letter, we report on spectrally resolved photoconductivity measurements of amorphous oxide semiconductor thin-film transistors. In contrast to previously reported photoconductive spectroscopy measurements recorded using spectrally filtered broadband light sources, we used a wavelength tunable picosecond laser to illuminate the thin-film. We extracted the absorption coefficient as a function of wavelength from the photocurrent measurement and showed that it followed the typical characteristic behaviour previously reported for amorphous oxide semiconductor thin-films. However, in addition, we observed several sharp spectral peaks in the photoconductivity spectrum which can be associated with sub-bandgap defects. These enhanced peaks are not normally visible in previously reported photoconductivity spectra. Furthermore, we show that we can control the sensitivity of our measurement by changing the applied gate bias voltage when the thin-films were fabricated into transistors. The enhancement achieved by using the wavelength tunable laser makes this a particularly sensitive characterisation tool and can additionally be used to discriminate between defects which have been incorporated after device fabrication. Published under license by AIP Publishing.