Comparative Studies on Ultraviolet-Light-Derived Photoresponse Properties of ZnO, AZO, and GZO Transparent Semiconductor Thin Films

Abstract

ZnO, Al-doped ZnO (AZO), and Ga-doped ZnO (GZO) semiconductor thin films were deposited on glass substrates via a sol-gel spin-coating process for application in a photoconductive ultraviolet (UV) detector. The doping concentrations of Al and Ga were 1.0 at % in the precursor solutions. In this study, the microstructural features and the optical and electrical properties of sol-gel-derived ZnO, AZO, and GZO thin films were compared, and the performance of ZnO-based UV photodetectors under ultraviolet A (UVA) light were measured. Experimental results confirmed the synthesis of single-phase nanocrystalline ZnO-based thin films and the successful substitution of Al and Ga into Zn sites in ZnO crystals. The results also demonstrated that the optical transmittance and electrical properties of ZnO thin films could be improved by Al and Ga doping. UV photodetectors based on ZnO-based thin films, having a metal-semiconductor-metal (MSM) configuration, were fabricated with Al inter-digitated electrodes. All photodetectors showed an ohmic nature between semiconductor and electrode contacts and exhibited a sharp increase in photocurrent under illumination with UVA light. We found that the MSM UV photodetector based on the GZO semiconductor thin film exhibited the best UV response (IUVA/Idark) of 73.3 and the highest photocurrent responsivity of 46.2 A/W under UVA light (power density ~0.825 mW/cm2) at 5 V bias.

Solution-Processed Mg-Substituted ZnO Thin Films for Metal-Semiconductor-Metal Visible-Blind Photodetectors

“…The presence of nano-sized pores is one of the major reasons why the electrical properties of solution-processed oxide semiconductor thin films are inferior to the sputtered oxide semiconductor thin films. However, the solution-processed oxide thin films exhibited a porous microstructure and had relatively large grain boundary areas, which could make them applicable as the sensing layer in sensors and detectors [6]. In addition, it can be clearly seen in Figure 3 that the particle sizes were significantly affected by the Mg content.…”

“…The photoconductivity gain, percentage of sensitivity, and responsivity are crucial parameters for evaluating and quantifying the performance of a photodetector [6,40]. The photoconductivity gain (K) is defined as the ratio of on current (I on ) per off current (I off ) and is expressed as:…”

“…ZnO is an n-type II-VI group semiconductor with a direct wide bandgap (~3.37 eV) and exhibits a wide range of electrical tenability. Its thermal, chemical, and mechanical stability at room temperature make it attractive for use in electronics, optoelectronics, and renewable energy generation [5,6]. The carriers of ZnO semiconductor thin films, originating from oxygen vacancies and zinc interstitials,…”

ZnO:Ga-graded ITO electrodes to control interface between PCBM and ITO in planar perovskite solar cells

“…In general, undoped ZnO films have poor electrical properties due to the low carrier concentration. Doping ZnO with appropriate III-group impurities (Al, Ga, or In) can increase the electrical conductivity and optical properties of ZnO thin films [29][30][31]. Al-, Ga-, and Indoped ZnO (AZO, GZO, and IZO) films are transparent to most of the solar spectrum used for photovoltaic solar cells, and their sheet resistances are comparable to those of ITO films.…”

Transparent Magnetoelectric Materials for Advanced Invisible Electronic Applications

“…[19,25,26] As a disruptive approach in this field, the development of optically transparent materials will expand the range of applications of ME materials. Thus, magnetic, conductive, semiconductive, and piezoelectric materials which are also flexible and transparent to the visible light are mentioned in the literature, [33][34][35][36][37][38] however, transparent and flexible ME materials capable of combining magnetic and electrical properties on a single compound are still underexplored. Thus, magnetic, conductive, semiconductive, and piezoelectric materials which are also flexible and transparent to the visible light are mentioned in the literature, [33][34][35][36][37][38] however, transparent and flexible ME materials capable of combining magnetic and electrical properties on a single compound are still underexplored.…”