An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivi...An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivity and photocarrier density at the heterojunction interface remains elusive. Herein, we have obtained the photoconductivity and photocarrier density of 173 nm Sb2Se3/Si(type-Ⅰ heterojunction) and 90 nm Sb2Se3/Si(type-Ⅱ heterojunction) utilizing terahertz(THz) time-domain spectroscopy(THz-TDS) and a theoretical Drude model. Since type-Ⅰ heterojunctions accelerate carrier recombination and type-Ⅱ heterojunctions accelerate carrier separation, the photoconductivity and photocarrier density of the type-Ⅱ heterojunction(21.8×10^(4)S·m^(-1),1.5 × 10^(15)cm^(-3)) are higher than those of the type-Ⅰ heterojunction(11.8×10^(4)S·m^(-1),0.8×10^(15)cm^(-3)). These results demonstrate that a type-Ⅱ heterojunction is superior to a type-Ⅰ heterojunction for THz wave modulation. This work highlights THz-TDS as an effective tool for studying photoconductivity and photocarrier density at the heterojunction interface. In turn, the intriguing interfacial photoconductivity effect provides a way to improve the THz wave modulation performance.展开更多
本文报道用分子束外延(Molecular Beam Epitaxy:MBE)技术制备了优良的铬(Cr)掺杂硒化铋(Cr-Bi_(2)Se_(3))薄膜样品。通过反射高能电子衍射(Reflective High Energy Electron Diffraction:RHEED)、X射线衍射(X-ray diffraction:XRD)技术...本文报道用分子束外延(Molecular Beam Epitaxy:MBE)技术制备了优良的铬(Cr)掺杂硒化铋(Cr-Bi_(2)Se_(3))薄膜样品。通过反射高能电子衍射(Reflective High Energy Electron Diffraction:RHEED)、X射线衍射(X-ray diffraction:XRD)技术和电磁输运系统对Cr-Bi_(2)Se_(3)进行测试。实验结果显示:较低的生长温度下Cr进入Bi_(2)Se_(3)中替代Bi位形成Cr Bi;较高的生长温度下Cr进入Bi_(2)Se_(3)中的范德瓦尔斯间隙形成层间(Interlayer)CrI,这一区别导致Cr-Bi_(2)Se_(3)在生长速率及磁性等方面表现出不同的性质。所以可以通过控制生长温度来调制Cr的掺杂位置,得到更理想的效果。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12261141662, 12074311, and 12004310)。
文摘An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivity and photocarrier density at the heterojunction interface remains elusive. Herein, we have obtained the photoconductivity and photocarrier density of 173 nm Sb2Se3/Si(type-Ⅰ heterojunction) and 90 nm Sb2Se3/Si(type-Ⅱ heterojunction) utilizing terahertz(THz) time-domain spectroscopy(THz-TDS) and a theoretical Drude model. Since type-Ⅰ heterojunctions accelerate carrier recombination and type-Ⅱ heterojunctions accelerate carrier separation, the photoconductivity and photocarrier density of the type-Ⅱ heterojunction(21.8×10^(4)S·m^(-1),1.5 × 10^(15)cm^(-3)) are higher than those of the type-Ⅰ heterojunction(11.8×10^(4)S·m^(-1),0.8×10^(15)cm^(-3)). These results demonstrate that a type-Ⅱ heterojunction is superior to a type-Ⅰ heterojunction for THz wave modulation. This work highlights THz-TDS as an effective tool for studying photoconductivity and photocarrier density at the heterojunction interface. In turn, the intriguing interfacial photoconductivity effect provides a way to improve the THz wave modulation performance.
文摘本文报道用分子束外延(Molecular Beam Epitaxy:MBE)技术制备了优良的铬(Cr)掺杂硒化铋(Cr-Bi_(2)Se_(3))薄膜样品。通过反射高能电子衍射(Reflective High Energy Electron Diffraction:RHEED)、X射线衍射(X-ray diffraction:XRD)技术和电磁输运系统对Cr-Bi_(2)Se_(3)进行测试。实验结果显示:较低的生长温度下Cr进入Bi_(2)Se_(3)中替代Bi位形成Cr Bi;较高的生长温度下Cr进入Bi_(2)Se_(3)中的范德瓦尔斯间隙形成层间(Interlayer)CrI,这一区别导致Cr-Bi_(2)Se_(3)在生长速率及磁性等方面表现出不同的性质。所以可以通过控制生长温度来调制Cr的掺杂位置,得到更理想的效果。
