Improving the photoresponsivity and reducing the persistent photocurrent effect of visible-light ZnO/quantum-dot phototransistors via a TiO₂ layer

Abstract

Conventional visible-light phototransistors based on the heterostructure of wide band gap zinc oxide (ZnO) and colloidal quantum-dots (CdSe/ZnS QDs) have been studied. However, it is found that there are various...

A visible-light phototransistor based on the heterostructure of ZnO and TiO2 with trap-assisted photocurrent generation

“…6b shows the photosensitivity of ZnO and TiO 2 (purge TTIP 10 s)/ZnO phototransistors under the exposure at the wavelength of 520 nm at a function of V G and V D = 20 V, which was plotted using the equation: where I light is the current in the phototransistor under the exposure of visible light, and I dark is the dark current. 19 The photosensitivity of the TiO 2 (purge TTIP 10 s)/ZnO phototransistor was superior to that of the ZnO phototransistor under visible light illumination. The maximum photosensitivity of the TiO 2 (purge TTIP 10 s)/ZnO phototransistor was 1.5 × 10 5 .…”

“… 12–18 However, heterojunction structure phototransistors have drawbacks such as poor uniformity, interface traps, and defect sites between other absorbing layers and oxide semiconductors. 19 In particular, traps at the interface deteriorate electrical characteristics with high-off current, low on/off ratio, and roll-off effects. 20 To resolve these problems, heterostructures based on oxide semiconductors have been suggested instead of organic and other nanomaterials on the wide bandgap oxide semiconductor.…”

Highly enhanced visible light photodetection properties of a ZnO phototransistor via an additional solution processed thin Al2O3 layer

“…The light power density was maintained at ∼1.2 mW cm −2 at a constant V G = −5.4 V and V D = 10 V. I light is the I D under light exposure, I dark is the I D without light exposure, A pt is the product of the channel width and length, A pd is the spot size of the laser source, J ph is the photocurrent density, and P is the power density of incident light. 34 The detailed values of photoresponsivity are summarized in Table 4. As shown in Fig.…”

Enhanced performance and stability in InGaZnO NIR phototransistors with alumina-infilled quantum dot solid

“…The numerical optoelectronic characteristics extracted under NIR (880 nm) at V GS = − 15 V and V DS = 0.1 V are shown in Table 1 . Photosensitivity (PS), photoresponsivity (PR), external quantum efficiency (EQE), and detectivity (D * ) were evaluated by the following equations 23 , 24 : …”