Huang Shiu-Ming, Hung Jai-Lung, Chou Mitch, Chen Chi-Yang, Liu Fang-Chen, Chen Ruei-San
Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
Center of Crystal Research, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
Sensors (Basel). 2021 Feb 23;21(4):1535. doi: 10.3390/s21041535.
Broadband photosensors have been widely studied in various kinds of materials. Experimental results have revealed strong wavelength-dependent photoresponses in all previous reports. This limits the potential application of broadband photosensors. Therefore, finding a wavelength-insensitive photosensor is imperative in this application. Photocurrent measurements were performed in SbTe flakes at various wavelengths ranging from visible to near IR light. The measured photocurrent change was insensitive to wavelengths from 300 to 1000 nm. The observed wavelength response deviation was lower than that in all previous reports. Our results show that the corresponding energies of these photocurrent peaks are consistent with the energy difference of the density of state peaks between conduction and valence bands. This suggests that the observed photocurrent originates from these band structure peak transitions under light illumination. Contrary to the most common explanation that observed broadband photocurrent carrier is mainly from the surface state in low-dimensional materials, our experimental result suggests that bulk state band structure is the main source of the observed photocurrent and dominates the broadband photocurrent.
宽带光电传感器已在各种材料中得到广泛研究。实验结果表明，在以往所有报告中都存在强烈的波长依赖性光响应。这限制了宽带光电传感器的潜在应用。因此，在该应用中找到一种对波长不敏感的光电传感器势在必行。在SbTe薄片中对从可见光到近红外光的各种波长进行了光电流测量。测得的光电流变化对300至1000nm的波长不敏感。观察到的波长响应偏差低于以往所有报告中的偏差。我们的结果表明，这些光电流峰的相应能量与导带和价带之间态密度峰的能量差一致。这表明观察到的光电流源于光照下这些能带结构峰的跃迁。与最常见的解释——观察到的宽带光电流载流子主要来自低维材料中的表面态——相反，我们的实验结果表明体态能带结构是观察到的光电流的主要来源，并主导宽带光电流。
