Silva Bruna, Rodrigues João, Sompalle Balaji, Liao Chun-Da, Nicoara Nicoleta, Borme Jérôme, Cerqueira Fátima, Claro Marcel, Sadewasser Sascha, Alpuim Pedro, Capasso Andrea
International Iberian Nanotechnology Laboratory, 4715-330 Braga, Portugal.
Centre of Physics, University of Minho, 4710-057 Braga, Portugal.
Nanomaterials (Basel). 2021 Jun 23;11(7):1650. doi: 10.3390/nano11071650.
Rhenium-based 2D transition metal dichalcogenides such as ReSe are suitable candidates as photoactive materials for optoelectronic devices. Here, photodetectors based on mechanically exfoliated ReSe crystals were fabricated using chemical vapor deposited (CVD) graphene single-crystal (GSC) as lateral contacts. A "pick & place" method was adopted to transfer the desired crystals to the intended position, easing the device fabrication while reducing potential contaminations. A similar device with Au was fabricated to compare contacts' performance. Lastly, a CVD hexagonal boron nitride (hBN) substrate passivation layer was designed and introduced in the device architecture. Raman spectroscopy was carried out to evaluate the device materials' structural and electronic properties. Kelvin probe force measurements were done to calculate the materials' work function, measuring a minimal Schottky barrier height for the GSC/ReSe contact (0.06 eV). Regarding the electrical performance, I-V curves showed sizable currents in the GSC/ReSe devices in the dark and under illumination. The devices presented high photocurrent and responsivity, along with an external quantum efficiency greatly exceeding 100%, confirming the non-blocking nature of the GSC contacts at high bias voltage (above 2 V). When introducing the hBN passivation layer, the device under white light reached a photo-to-dark current ratio up to 10.
铼基二维过渡金属二硫属化物，如ReSe，是光电器件光活性材料的合适候选者。在此，基于机械剥离的ReSe晶体的光电探测器是使用化学气相沉积（CVD）石墨烯单晶（GSC）作为横向接触来制造的。采用“拾取与放置”方法将所需晶体转移到预期位置，简化了器件制造过程，同时减少了潜在污染。制造了一个带有金的类似器件来比较接触性能。最后，在器件结构中设计并引入了CVD六方氮化硼（hBN）衬底钝化层。进行拉曼光谱以评估器件材料的结构和电子性质。进行开尔文探针力测量以计算材料的功函数，测量出GSC/ReSe接触的最小肖特基势垒高度为0.06 eV。关于电学性能，I-V曲线显示GSC/ReSe器件在黑暗和光照下都有可观的电流。这些器件呈现出高光电流和响应度，以及大大超过100%的外量子效率，证实了GSC接触在高偏置电压（高于2 V）下的无阻性质。当引入hBN钝化层时，白光下器件的光电流与暗电流之比高达10。
