Search

Owing to the intrinsically wide bandgap and high uniformity, amorphous Ga2O3 (a-Ga2O3) has been illustrating a great industrial potential for large-area deep ultraviolet (UV) photosensor arrays. However, a seemingly irreconcilable contradiction between high responsivity and long persistent photoconductivity has hampered the growing pace of such devices. In this work, three-terminal InGaZnO (IGZO)/a-Ga2O3 dual-active-layer (DAL) transistors were developed to realize the ability of a-Ga2O3 as the active layer both in switching and sensing. Benefitting from the introduction of ultrathin IGZO electron reservoir and defect control of a-Ga2O3, the DAL device demonstrates more stable and superior gate-control capability with promising performance including high on/off ratio and field-effect mobility of ∼108 and 8.3 cm2/V⋅s, respectively, as well as a small sub-threshold swing (SS) of 0.36 V/dec. Under 254 nm UV illumination, the DAL device manifests a light-to-dark ratio of ∼108, a responsivity of 4.8 × 103 A W−1, a detectivity of 8 × 1015 Jones, and a UV/visible rejection ratio (R254/R400) of 64. The simultaneous achievement of deep UV photo-detection and transistor's switching performance in a-Ga2O3 material offers excellent potential for the construction of large-area active-matrix UV photosensor arrays with the simple and low-cost fabrication process. [ABSTRACT FROM AUTHOR]

InGaZnO high-voltage thin-film transistors (HV-TFTs) with vertical dual-active-layer structure and lateral offset design were fabricated at low temperature. The TFT features such as sub-threshold swing, threshold voltage, and hysteresis voltage are similar to those of the normal devices; furthermore, they are independent of the offset length. The blocking voltage of HV-TFTs with an offset of 10 μm is 406 ± 17 V while the ON/OFF ratio reaches 109 at. [ABSTRACT FROM AUTHOR]

A three‐terminal thin‐film transistor (TFT) architecture is essential for photodetectors to reach a good balance between high responsivity and fast response speed. Bottom‐gate amorphous Ga2O3 (a‐Ga2O3) TFTs are fabricated to boost their UV photodetection properties. During the device fabrication process, a simple chemical‐etching solution with the advantages of easy operation, low cost, and compatibility with traditional lithography process, is developed to selectively etch a‐Ga2O3 films. The a‐Ga2O3 channel etched device on Si manifests an effective suppression of the commonly observed gate leakage current. Meanwhile, a patterned a‐Ga2O3 TFT on quartz shows an excellent n‐type TFT performance with an on/off ratio as high as ≈107. It is further applied as a phototransistor, to diminish the persistent photoconductivity (PPC) effect while keeping a high responsivity (R) as well. Under the 254 nm UV illumination, the a‐Ga2O3 phototransistor demonstrates a high light‐to‐dark ratio of 5 × 107, a high responsivity of 5.67 × 103 A W−1, and a high detectivity of 1.87 × 1015 Jones. Remarkably, the PPC phenomenon in a‐Ga2O3 UV phototransistors is effectively suppressed by applying a positive gate pulse, which greatly shortens the decay time to 5 ms and offers a‐Ga2O3 possible inroads into imaging applications. [ABSTRACT FROM AUTHOR]

Negative drain currents under positive drain-to-gate voltage were found in the OFF-state transfer curves of thin-film transistors (TFTs). A dynamic model was developed, by accounting for capacitances, to interpret the phenomenon. The capacitor discharging during gate voltage sweeping leads to the negative currents. Test conditions and intrinsic device parameters affect the existence of this phenomenon, which is verified by our experimental results of InGaZnO TFTs. [ABSTRACT FROM AUTHOR]

In this paper, we report the fabrication of flexible and transparent InGaZnO thin-film transistors on muscovite mica substrates. The mica substrate is compatible with four-step photolithographic processes as well as high-temperature processes. The field-effect mobility, subthreshold swing, ON/OFF ratio, threshold voltage, and hysteresis voltage are improved after annealing both at 300° C and 400° C in nitrogen. The device demonstrates more stable performance under positive gate bias stress when annealed at 400° C than at 300° C. The electrical performances are stable when exposed to tensile bending cycles up to 10 000 times. The mica with devices shows small optical loss in the visible region, where the average transmittance is as high as 86.75%. [ABSTRACT FROM AUTHOR]

Abstract We report the realization of flexible fully-transparent high-voltage (HV) inverters composed with a high-voltage thin film transistor (HVTFT) drive and an on-chip high-voltage thin film diode (HVTFD) load. The overall fabrication temperatures are decreased as low as 75 °C to minimize the built-in strain caused by the large thermal expansion mismatch. High on/off ratio of 1010, rectification ratio of 109 and voltage gain of 8.5 are achieved in the flexible HVTFT, HVTFD and HV inverter, respectively. In addition, the flexible HV devices are fabricated with a novel self-aligned photolithography technology, and the fabrication procedure and working principle are depicted in this letter. This work combines HV electronics with the upsurging flexible transparent electronics, and will initiate interdisciplinary researches between the two fields. Graphical abstract Unlabelled Image Highlights • A self-aligned photolithography process is presented. • The mechanism of the process is studied with TCAD simulation. • High performance high-voltage devices are achieved with this process. [ABSTRACT FROM AUTHOR]

Flexible transparent ZnO thin-film transistors (TFTs) have gained momentum during the last decade because of the increasingly emerging demands in flexible transparent displays and wearable electronics industry. However, the instability issue regarding a deviation of turn-on voltage under gate bias stress has remained unsettled, greatly impeding the progress towards practical applications. Here we present a solution to this problem by adopting a new dual-source device architecture to self-diagnose and pull back the deviated turn-on voltage. The dual-source TFTs were fabricated on PEN substrate by conventional UV photolithography with ZnO channel prepared by magnetron sputtering technique. By combining the presented device architecture with a rapid correction process, the turn-on voltage shift was reduced to 0.1 V under −15 V gate voltage bias stress of 5000 s, which favors low power consumption circuits by preventing the TFTs drifting from enhancement to depletion mode. To illustrate its unique working mechanism, device physics simulation, square-law model deduction and circuit current analysis were carried out. The methodology we developed enhances the stability of flexible transparent oxide TFTs and can be adapted in other microelectronic and optoelectronic devices. • Flexible fully transparent thin-film transistors are fabricated. • Novel dual-source transistor structure is presented. • The gate bias instability problem can be readily solved. • TCAD device simulation is conducted to study the working principle. [ABSTRACT FROM AUTHOR]