Supporting Information Direct Synthesis and Practical Bandgap ...
Supporting Information
Direct Synthesis and Practical Bandgap Estimation of Multilayer Arsenene Nanoribbons Hsu-Sheng Tsai1*, Sheng-Wen Wang2, Ching-Hung Hsiao3, Chia-Wei Chen3, Hao Ouyang3, Yu-Lun Chueh3, Hao-Chung Kuo2, Jenq-Horng Liang1,4* 1
Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan, R.O.C. 2
3
Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30013, Taiwan, R.O.C
Department of Material Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan, R.O.C. 4
Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, R.O.C.
*Correspondence to: [email protected] and [email protected]
Experiments Intrinsic InAs (001) substrates were used as the templates, in which the arsenic element is the source of the formation of multilayer arsenene. The InAs substrates were first immersed in the N2 plasma produced by a radio frequency (13.56 MHz) system with a power of 50-200 W for 30-60 minutes under ~10−1 torr. After plasma immersion, the samples were annealed at 450˚C in N2/H2 (10/1, v/v) ambiance for 10-180 minutes. The N2 should be mixed with H2 for the prevention of arsenic oxidation caused by the leakage of O2. Raman analysis was implemented by the confocal micro-Raman spectrometer (HORIBA, LabRAM, HR800 UV) to be certain of the formation of arsenene layers. The light source of the Raman spectrometer is a He-Cd laser with a 325 nm wavelength and a power of 30 mW. Surface composition was analyzed using XPS (Ulvac-PHI, Versaprobe II) to realize the formation mechanism of gray multilayer arsenene. The spherical-aberration corrected TEM (JEOL, JEM-ARM200FTH) with 0.1 nm resolution of the lattice image and 200 kV accelerated voltage was employed to observe the nano-scale layer structure. The distribution of depth concentration was monitored by SIMS (CAMECA, IMS 7F) with an O2+ sputtering ion source. The bandgap of arsenene layers was estimated by a PL spectrometer (HORIBA, iHR550) with a 395 nm-laser.
Calculations The diffraction pattern in Figure 3a could be used to derive the interplanar distances. In Figure S1a, the length of the dashed line, which contains a quadruple reciprocal vector, is equal to 13.97 nm-1, so that the length of the reciprocal vector is 3.4925 nm-1. The inverse of 3.4925 nm-1 is equal to 0.286 nm that corresponds to the (110) interplanar distance (0.277 nm) of multilayer arsenene. On the other hand, the length (11.04 nm-1) of the dashed line as shown in Figure S1b contains a double reciprocal vector. Hence, the length of the reciprocal vector is 5.52 nm-1. The inverse of 5.52 nm-1 is equal to 0.181 nm that corresponds to the (01-1) interplanar distance (0.188 nm) of multilayer arsenene. These calculations, which derived from the experimental results, are in agreement with the theory and the error rate is less than 5%, indicating that the results are believable.
Figure S1. (a) The distance between (110) reciprocal points of multilayer arsenene, (b) The distance between (01-1) reciprocal points of multilayer arsenene.
Figure S2. The TEM image of the region with narrower multilayer arsenene nanoribbons.
Direct Synthesis and Practical Bandgap Estimation of Multilayer Arsenene Nanoribbons Hsu-Sheng Tsai1*, Sheng-Wen Wang2, Ching-Hung Hsiao3, Chia-Wei Chen3, Hao Ouyang3, Yu-Lun Chueh3, Hao-Chung Kuo2, Jenq-Horng Liang1,4* 1
Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan, R.O.C. 2
3
Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30013, Taiwan, R.O.C
Department of Material Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan, R.O.C. 4
Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan, R.O.C.
*Correspondence to: [email protected] and [email protected]
Experiments Intrinsic InAs (001) substrates were used as the templates, in which the arsenic element is the source of the formation of multilayer arsenene. The InAs substrates were first immersed in the N2 plasma produced by a radio frequency (13.56 MHz) system with a power of 50-200 W for 30-60 minutes under ~10−1 torr. After plasma immersion, the samples were annealed at 450˚C in N2/H2 (10/1, v/v) ambiance for 10-180 minutes. The N2 should be mixed with H2 for the prevention of arsenic oxidation caused by the leakage of O2. Raman analysis was implemented by the confocal micro-Raman spectrometer (HORIBA, LabRAM, HR800 UV) to be certain of the formation of arsenene layers. The light source of the Raman spectrometer is a He-Cd laser with a 325 nm wavelength and a power of 30 mW. Surface composition was analyzed using XPS (Ulvac-PHI, Versaprobe II) to realize the formation mechanism of gray multilayer arsenene. The spherical-aberration corrected TEM (JEOL, JEM-ARM200FTH) with 0.1 nm resolution of the lattice image and 200 kV accelerated voltage was employed to observe the nano-scale layer structure. The distribution of depth concentration was monitored by SIMS (CAMECA, IMS 7F) with an O2+ sputtering ion source. The bandgap of arsenene layers was estimated by a PL spectrometer (HORIBA, iHR550) with a 395 nm-laser.
Calculations The diffraction pattern in Figure 3a could be used to derive the interplanar distances. In Figure S1a, the length of the dashed line, which contains a quadruple reciprocal vector, is equal to 13.97 nm-1, so that the length of the reciprocal vector is 3.4925 nm-1. The inverse of 3.4925 nm-1 is equal to 0.286 nm that corresponds to the (110) interplanar distance (0.277 nm) of multilayer arsenene. On the other hand, the length (11.04 nm-1) of the dashed line as shown in Figure S1b contains a double reciprocal vector. Hence, the length of the reciprocal vector is 5.52 nm-1. The inverse of 5.52 nm-1 is equal to 0.181 nm that corresponds to the (01-1) interplanar distance (0.188 nm) of multilayer arsenene. These calculations, which derived from the experimental results, are in agreement with the theory and the error rate is less than 5%, indicating that the results are believable.
Figure S1. (a) The distance between (110) reciprocal points of multilayer arsenene, (b) The distance between (01-1) reciprocal points of multilayer arsenene.
Figure S2. The TEM image of the region with narrower multilayer arsenene nanoribbons.
