Deep-Ultraviolet (DUV)-Induced Doping in Single Channel Graphene for Pn-Junction

Abstract

The electronic properties of single-layer, CVD-grown graphene were modulated by deep ultraviolet (DUV) light irradiation in different radiation environments. The graphene field-effect transistors (GFETs), exposed to DUV in air and pure O2, exhibited p-type doping behavior, whereas those exposed in vacuum and pure N2 gas showed n-type doping. The degree of doping increased with DUV exposure time. However, n-type doping by DUV in vacuum reached saturation after 60 min of DUV irradiation. The p-type doping by DUV in air was observed to be quite stable over a long period in a laboratory environment and at higher temperatures, with little change in charge carrier mobility. The p-doping in pure O2 showed ~15% de-doping over 4 months. The n-type doping in pure N2 exhibited a high doping effect but was highly unstable over time in a laboratory environment, with very marked de-doping towards a pristine condition. A lateral pn-junction of graphene was successfully implemented by controlling the radiation environment of the DUV. First, graphene was doped to n-type by DUV in vacuum. Then the n-type graphene was converted to p-type by exposure again to DUV in air. The n-type region of the pn-junction was protected from DUV by a thick double-coated PMMA layer. The photocurrent response as a function of Vg was investigated to study possible applications in optoelectronics.

Self-biased wavelength selective photodetection in an n-IGZO/p-GeSe heterostructure by polarity flipping

“…Transparent semiconductor oxides have been extensively studied as new materials applied to thin-film transistors and photosensors due to their remarkable characteristics, including high mobility, low leakage current, small sub-threshold swing, wafer-scale deposition, and high electrical reliability and sensitivity. [1][2][3][4][5][6] Among the semiconductor oxides, indium gallium zinc oxide (n-IGZO), a wide bandgap semiconductor with a bandgap of ∼3.1-3.8 eV and stoichiometrically associated n-type conductivity (In : Ga : Zn = 1 : 1 : 1 atomic ratio), has been considered a viable candidate for transparent display applications. n-IGZO also has good uniformity, low-temperature processing, high optical transparency, good bias-thermal stress (BTS) stability, and chemical stability.…”