P–n homo-junction arrays of aligned single walled carbon nanotubes fabricated by selectivepatterning of polyethyleneimine film

Abstract

We describe the fabrication and electrical performance of p–n homo-junctiondiode arrays of horizontally aligned single walled carbon nanotubes (SWCNTs).Horizontally aligned SWCNTs grown on stable temperature-cut quartz with a density of ∼ 6 SWCNTsµm − 1 were transferredonto a SiO2/Si substrate. After the electrical breakdown, aligned SWCNT field effecttransistors (FETs) showed unipolar p-type characteristics with a large currenton/off ratio of106 at 1 V and a holemobility per tube of 1500 cm2 V − 1 s − 1. Spin-coating of polyethyleneimine (PEI) onto p-type SWCNT FETs showedthe n-type transfer characteristics. Patterning of spin-coated PEI film enabledthe fabrication of p–n homo-junction arrays of aligned SWCNTs in an easyway, where the rectifying behavior was observed with a rectification ratio of ∼ 104 at ± 2 V. A comparative study with a p–n homo-junction of random networks of SWCNTsconfirmed the advantage of aligned SWCNTs for applications in high performanceelectronic devices.