Molecule Charge Transfer Doping for p‐Channel Solution‐Processed Copper Oxide Transistors

Abstract

The doping of semiconductors plays a critical role in improving the performance of modern electronic devices by precisely controlling the charge carrier density. However, the absence of a stable doping method for p‐type oxide semiconductors has severely restricted the development of metal oxide‐based transparent p–n junctions and complementary circuits. Here, an efficient and stable doping process for p‐type oxide semiconductors by using molecule charge transfer doping with tetrafluoro‐tetracyanoquinodimethane (F4TCNQ) is reported. The selections of a suitable dopant and geometry play a crucial role in the charge‐transfer doping effect. The insertion of a F4TCNQ thin dopant film (2–7 nm) between a Au source‐drain electrode and solution‐processed p‐type copper oxide (CuxO) film in bottom‐gate top‐contact thin‐film transistors (TFTs) provides a mobility enhancement of over 20‐fold with the desired threshold voltage adjustment. By combining doped p‐type CuxO and n‐type indium gallium zinc oxide TFTs, a solution‐processed transparent complementary metal‐oxide semiconductor inverter is demonstrated with a high gain voltage of 50. This novel p‐doping method is expected to accelerate the development of high‐performance and reliable p‐channel oxide transistors and has the potential for widespread applications.

Engineering Copper Iodide (CuI) for Multifunctional p‐Type Transparent Semiconductors and Conductors

“…Another problem is that it is difficult to p‐dope the TS/C because of defect compensation. [ 12 , 13 ]…”

“…As for the p‐type semiconductors, only Cu 2 O, SnO, NiO, and Rh 2 O 3 were demonstrated as potential candidates, but they suffered from insufficient hole transport with low mobility and inadequate optical transparency. [ 9 , 11 , 12 ]…”

Enabling three-dimensional porous architectures via carbonyl functionalization and molecular-specific organic-SERS platforms

“…Their ability to form nano-/micro-structured thin-films from solution or vapor phase with tunable morphologies and optoelectronic properties has greatly benefited the research for next-generation optoelectronic devices 10 – 12 . Although most of these device technologies, such as organic field-effect transistors (OFETs) 13 – 15 or light-emitting diodes 16 , have now become a conventional application avenue for molecular semiconductors, they hold huge promise also for unconventional applications such as surface-enhanced Raman spectroscopy (SERS). As we have recently disclosed in our pioneering studies 17 , 18 , the nanostructured organic films of π-electron-deficient fluorinated oligothiophene semiconductors DFH-4T 17 and DFP-4T 18 , fabricated via physical vapor deposition (PVD), enabled the Raman detection of organic analytes (e.g., methylene blue (MB) and rhodamine 6 G) without needing a metallic or an inorganic layer.…”

8‐5: Invited Paper: P‐Type Oxide Semiconductors for Displays: Material Design and Field‐Effect Devices

“…The poor electrical performances of Cu2O TFTs was attributed to a high density of defects at grain boundaries and at the semiconductor/dielectric interface, e.g., VOs and CuO secondary phase [21]. Several strategies are proposed to control these defects and to improve the performance and stability of Cu2O TFTs, including surface passivating [22,23], doping [24], using high-κ gate dielectrics (Al2O3, HfO2) [6]. For example, Chang and Nomura et al recently demonstrated the use of sulfur to reduce back-channel defect of p-type CuxO TFTs and achieved μsat of 1.38 cm 2 /Vs and on/off ratio of 4.1 × 10 6 [21].…”