ABSTRACT
Electronic devices composed of semiconducting two-dimensional (2D) materials and ultrathin 2D metallic electrode materials, accompanying synergistic interactions and extraordinary properties, are becoming highly promising for future flexible and transparent electronic and optoelectronic device applications. Unlike devices with bulk metal electrode and 2D channel materials, devices with ultrathin 2D electrode and 2D channel are susceptible to chemical reactions in both channel and electrode surface due to the high surface to volume ratio of the 2D structures. However, so far, the effect of doping was primary concerned on the channel component, and there is lack of understanding in terms of how to modulate electrical properties of devices by engineering electrical properties of both the metallic electrode and the semiconducting channel. Here, we propose the novel, one-pot doping of the field-effect transistor (FET) based on 2D molybdenum disulfide (MoS2) channel and ultrathin copper sulfide (CuS) electrodes under mild iodine gas environment at room temperature, which simultaneously modulates electrical properties of the 2D MoS2channel and 2D CuS electrode in a facile and cost-effective way. After one-pot iodine doping, effective p-type doping of the channel and electrode was observed, which was shown through decreased off current level, improvedIon/Ioffratio and subthreshold swing value. Our results open up possibility for effectively and conveniently modulating electrical properties of FETs made of various 2D semiconductors and ultrathin contact materials without causing any detrimental damage.
ABSTRACT
Objective To analyze the epidemiological characteristics of Mycobacterium tuberculosis by enterbaeterial repetitive intergenic consensus-polymerase chain reaction(ERIC-PCR)DNA fingerprint. Methods Mycobacterium tuberculosis positive sputum samples between September 2003 to May 2006 were collected and cultured.Chromosomal DNA were extracted and ERIC-PCR DNA fingerprinting was analyzed by software,such as RAPD PHYLIP and Treeview.Results A total of 42 different fingerprints were detected.Phylogenetic analysis showed that they could be classified into three clusters,the clustering rate was 72.6%.The characteristics of ERIC-PCR fingerprint patterns were related to age,drug resistance,and type of resistance.Conclusions ERIC-PCR DNA fingerprinting technique used in this study is good for epidemiological studies with its strong discrimination,simplicity and rapidness.A high level of recent transmission is found in our city.