Novel Method for Fabricating Visible-Light Phototransistors Based on a Homojunction-Porous IGZO Thin Film Using Mechano-Chemical Treatment

Abstract

A homojunction-structured oxide phototransistor based on a mechano-chemically treated indium–gallium–zinc oxide (IGZO) absorption layer is reported. Through this novel and facile mechano-chemical treatment, mechanical removal of the cellophane adhesive tape induces reactive radicals and organic compounds on the sputtered IGZO film surface. Surface modification, following the mechano-chemical treatment, caused porous sites in the solution-processed IGZO film, which can give rise to a homojunction-porous IGZO (HPI) layer and generate sub-gap states from oxygen-related defects. These intentionally generated sub-gap states played a key role in photoelectron generation under illumination with relatively long-wavelength visible light despite the wide band gap of IGZO (>3.0 eV). Compared with conventional IGZO phototransistors, our HPI phototransistor displayed outstanding optoelectronic characteristics and sensitivity; we measured a threshold voltage (V th) shift from 3.64 to −6.27 V and an on/off current ratio shift from 4.21 × 1010 to 4.92 × 102 under illumination with a 532 nm green light of 10 mW/mm2 intensity and calculated a photosensitivity of 1.16 × 108. The remarkable optoelectronic characteristics and high optical transparency suggest optical sensor applications.

Probing the Efficacy of Large-Scale Nonporous IGZO for Visible-to-NIR Detection Capability: An Approach toward High-Performance Image Sensor Circuitry

“…Herein, block copolymer (polystyrene- co -poly­(methyl methacrylate)) lithography is employed to create a uniform, equidistant, and periodic array of nanopores in the IGZO semiconducting channel throughout the 4″ wafer. The functionalized edges of the nanopores lead to the generation of cation and/or anion vacancies without changing the IGZO composition . The presence of all the elements after making nanopores is confirmed by transmission electron microscopy with energy dispersion spectroscopy (TEM-EDS) and X-ray photoelectron spectroscopy (XPS).…”

“…The functionalized edges of the nanopores lead to the generation of cation and/or anion vacancies without changing the IGZO composition. 27 The presence of all the elements after making nanopores is confirmed by transmission electron microscopy with energy dispersion spectroscopy (TEM-EDS) and X-ray photoelectron spectroscopy (XPS). Thus, a deliberate introduction of the edge in a nanopore can dictate the subgap states within the bandgap of IGZO.…”

Facile Polydimethylsiloxane Treatment of Indium Gallium Zinc Oxide Phototransistor for Visible Light‐Based Multilevel Photomemory

“…[33,34] Therefore, carbon by PDMS residues decomposed during the thermal annealing process causes the decrease of M-O and the increase of V O by attracting oxygen in the front channel of IGZO. [35] In addition, hydrogen and carbon in decomposed PDMS residues react with oxygen to form hydroxide species (-OH) and metal oxide-carbon (M-OC) attributed to M-OH, [36,37] thereby increasing the proportion of M-OH compared to IGZO without PDMS treatment. From these analyses, PDMS treatment resulted in the formation of V O and M-OH by generating subgap states by hydrogen and carbon included in PDMS residues.…”

Photo-response modulation of organic transistors for multi-level light sensing using active layer microstructure control

“…27,33 The effect of structural variations of active layers on photo-responsivity has been studied in some detail, such as solvent effect on bulk heterojunction-based devices, 34 layer structure of organic composites, 35,36 or the effect of morphology on phototransistors with inorganic semiconductors. [37][38][39] On the other hand, the impact of annealing processes and the change in morphology on the photo-response characteristics of OPTs has not yet been studied.…”