p-n hetero-junction diode arrays of p-type single walled carbon nanotubes and aligned n-type SnO₂ nanowires.
p-n hetero-junction diode arrays were fabricated using specific direct techniques for the transfer of p-type single walled carbon nanotubes (SWCNTs) and aligned n-type SnO₂ nanowires (NWs) onto a patterned substrate surface. Their electronic and optoelectronic properties were characterized. Perpendicular crossings of the p- and the n-channels with each other were confirmed by transfer characteristics with respect to the bottom gate. The resulting diode showed a good rectifying behavior with a rectification ratio of over 10² at ±5 V, where the equivalent circuit model of a serially connected diode and resistor was used for analysis of the electrical properties. Both the forward and the reverse currents were observed to increase with the application of a positive gate bias, indicating an n-type gate dependence. Under a forward bias, the dominant contribution of the SnO₂ NW channel to the total resistance of the equivalent model is attributed to the n-type gate dependence since the resistance of the n-channel increased with a negative gate bias, resulting in the decrease of the forward current. Under a reverse bias, positive gate increased the concentration of valence electrons in the SWCNTs, enhancing direct tunneling to the conduction band of the SnO₂ NWs. High sensitivity to UV irradiation under the reverse bias was also demonstrated with a photosensitivity over 10², suggesting potential applicability of the hetero-junction diodes in optoelectronic devices.
Department of Chemical and Biological Engineering, Korea University, Seoul 136-701, Korea.
Jangyeol
J
Yoon
Kyung Whon
KW
Min
Joonsung
J
Kim
Gyu Tae
GT
Kim
Jeong Sook
JS
Ha
D004581:Electronics / Q000295:instrumentation; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D053770:Nanowires / Q000737:chemistry* / Q000706:statistics & numerical data; D017971:Tin Compounds / Q000737:chemistry*
D037742:Nanotubes, Carbon; D017971:Tin Compounds; C045358:stannic oxide