A three-terminal ultraviolet photodetector constructed on a barrier-modulated triple-layer architecture

Abstract

We report a novel three-terminal device fabricated on MgZnO/ZnO/MgZnO triple-layer architecture. Because of the combined barrier modulation effect by both gate and drain biases, the device shows an unconventional I-V characteristics compared to a common field effect transistor. The photoresponse behavior of this unique device was also investigated and applied in constructing a new type ultraviolet (UV) photodetector, which may be potentially used as an active element in a UV imaging array. More significantly, the proper gate bias-control offers a new pathway to overcome the common persistent photoconductivity (PPC) effect problem. Additionally, the MgZnO:F as a channel layer was chosen to optimize the photoresponse properties, and the spectrum indicated a gate bias-dependent wavelengthselectable feature for different response peaks, which suggests the possibility to build a unique dualband UV photodetector with this new architecture.The classic three-terminal device such as field-effect transistor (FET) is, and always has been, the workhorse of the microelectronics industry. Today, as metal-oxide-semiconductor FET (MOSFET) technology gains a huge commercialized market, coupled with the sharp growth in oxide semiconductors thin film transistor (TFT) for displays, the demand for FETs continues to increase throughout the world-wide microcircuits, and has led to a rapid expansion of microprocessors, memory chips and active matrix et al. over the last more than four decades [1][2][3] . Despite these advantages of the transistors, the intrinsic advantage of three-terminal device has been proved as one of the best candidates for improving the low power consumption and high-sensitivity ultraviolet photodetectors (UV-PDs) such as ZnO based photodetectors 4-6 . As we all know, different types of UV-PDs based on ZnO have been reported early from 1950s 7,8 ; however, they mainly utilize two terminal devices, which include photoconductive, Schottky, and p/n-junction types 9-12 . Moreover, for these structures, there are two critical drawbacks to be overcome before the ZnO UV-PDs constructed on UV imaging or other applications: 1) The persistent photoconductivity (PPC) effect, which was extensively ascribed to the existence of metastable shallow donor state of oxygen vacancy (V O ) located within the bandgap of ZnO [13][14][15][16] . Especially under the illumination of short-wavelength light, the PPC can cause the semiconductor material to remain conductive for hours/days, even in the absence of light. This increases the response times and limits the frame rates. 2) Low photo gain. A high performance UV-PDs needs high sensitivity. However, due to the high background carrier concentration and low photo gain, most UV-PDs suffer from low discrimination ratio between UV and dark/visible light, which limits the application of UV-PDs [17][18][19] . To suppress the PPC effect in oxide UV-PDs and amplify the photo gain, the ability of three terminal photo-TFTs in controlling the position of the Fermi level and carrier densities has ...

Enhancement of Responsivity in Solar-Blind UV Detector With Back-Gate MOS Structure Fabricated on β-Ga2O3 Films

“…This indicates that this PD works properly as a Schottky barrier phototransistor. Similar three-terminal PDs have been constructed on MgZnO/ZnO/MgZnO/Si, which showed the same modulation (Ye et al, 2016). Furthermore, we find that I p is proportional to the light intensity when the device is exposed to different light powers (the result is not shown here), that is to say, the device performance is affected by the tested light intensity, as reported on the similar PDs (Feng et al, 2018).…”

Boosted UV Photodetection Performance in Chemically Etched Amorphous Ga2O3 Thin‐Film Transistors

“…[ 1–4 ] So far two‐terminal Ga 2 O 3 photodetectors (PDs) are the most commonly investigated, but a slow response speed caused by persistent photoconductivity (PPC) effect [ 5,6 ] impedes the further promotion of devices' performance. [ 7 ] As is well known to all, PPC phenomenon occurs in most oxide semiconductor materials owing to the large quantity of oxygen vacancy ( V o ) defects and high density of trap states. [ 8,9 ]…”

High-Performance Solar-Blind UV Phototransistors Based on ZnO/Ga2O3 Heterojunction Channels

“…The photovoltaic PD is built upon the foundation of having an in-built charge separation mechanism and has a faster response time − but the detection signal cannot be amplified. In contrast, a three-terminal phototransistor with one more terminal-gate to flexibly control the carrier transport is attractive for UV PDs. − Although Ga 2 O 3 phototransistor PDs have been demonstrated previously, most of them are based on high-cost mechanical exfoliated single-crystal Cr-doped Ga 2 O 3 . In addition, the dark current is usually high leading to high power consumption and introduce interference to image application or communication application .…”