國立中興大學物理學系暨奈米科學研究所

 

 

The next generation of nanotechnology devices based on quantum technologies that are being developed in research laboratories can demonstrate enhanced efficiency and performance compared to current technologies. However, devices are usually only ‘one-off’, individual examples. To fulfill their significant potential, it is essential to consider the scalability, reliability, and integration of devices in quantum circuits. I will present a solution given by multiplexing schemes developed at Cambridge University, U.K. [1], which integrates devices at the forefront of physics research based on semiconductor HEMTs, nanowires [1], as well being compatible with integration of arrays of arbitrary 2D nanomaterials and semiconductor nanowires [2]. The architecture overcomes limitations of the number of wires in cryogenic apparatus in which these devices are usually measured, and device numbers can be increased exponentially. This presents a significant shift in research protocols used in the lab. The reproducibility of quantum phenomena and yield can be studied in previously inaccessible device numbers, assessing applicability to practical applications. Systematic variations of device dimensions can be comprehensively investigated to optimize designs and understand the impact on performance. Thirdly, measuring large numbers allows statistical analysis of data, revealing trends in electron transport phenomena that cannot be determined from previous techniques. This approach can also lead to new device development by discovering unique devices with unusual properties [3]. Identifying the underlying device conditions leading to their behavior allows the reverse engineering of reproducible structures. We find that graphene grown by chemical vapor deposition—where device quality is typically limited by the fabrication processes required—hosts a magnetic-field driven energy gap at charge neutrality, leading to diverging resistance. This signature of high-quality electronic behavior is previously only seen in devices fabricated using more complex techniques that limit scalability. Our results indicate the existence of a high-quality region in a narrow constriction where edge disorder is minimized, suggesting edge disorder as a key factor in determining electronic quality. The scalable methods used in fabricating this device suggests the possibility of creating high quality devices from 2D material for investigating exotic phenomena, using only conventional fabrication techniques.
[1] H. Al-Taie, L. W. Smith et al., Cryogenic on-chip multiplexer for the study of quantum transport in 256 split-gate devices Appl. Phys. Lett. 102, 243102 (2013).
[2] L. W. Smith et al., High-Throughput Electrical Characterisation of Nanomaterials from Room to Cryogenic Temperatures ACS Nano 14, 15293 (2020).
[3] L. W. Smith et al., Giant Magnetoresistance in a CVD Graphene Constriction ACS Nano 16, 2833 (2022).