Pei-Wen Li

High-Performance Submicrometer ZnON Thin-Film Transistors With Record Field-Effect Mobility

In this letter, we demonstrate 0.6-μm ZnON thin-film transistors (TFTs) with the field-effect mobility of 71 cm2/V-sec, which to the best of our knowledge is the highest value ever reported on submicrometer oxide-semiconductor TFTs. The drive current, field-effect mobility, and subthreshold slope of ZnON TFTs are significantly improved as compared with their counterpart ZnO TFTs of the same channel dimensions and structure. Such an improvement in the field-effect mobility primarily results from a considerable reduction in the series source/drain (S/D) resistances because of suppression in an interfacial layer formation between Al S/D pads and the channel layer.

Film-profile-engineered IGZO thin-film transistors with gate/drain offset for high voltage operation

IGZO transistors with various gate/drain-offset lengths (Lgdo) were fabricated with the film-profile-engineering method. Breakdown voltage (VBD) of the fabricated devices increases while transconductance (gm) decreases with increasing Lgdo. In contrast, threshold voltage and subthreshold swing remain relatively unchanged. Vbd of ~80 V is obtained with Lgdo of 0.3 μm. Output characteristics with operation voltage up to 50 V are also demonstrated, evidencing the capability of the device for high-voltage operation. Impact of hot-carrier stress is also investigated in this work.

Au Nanoparticle Light Scattering Enhanced Responsivity in Pentacene Phototransistor for Deep-UV Light Detection

In this letter, a pentacene thin-film phototransistor (PTFP) with gold nanoparticles (Au-NPs) decoration in bottom-gate structure was demonstrated. With the Au-NPs, this device is capable of scattering the free-space ultra-violet (UV) irradiation into the pentacene film. Therefore, the PTFP with Au-NPs exhibit 4.5-A/W responsivity with VGS = 0 V at the wavelength of 240 nm. Meanwhile, an ultimate 32.4-A/W responsivity can be achieved with VGS = -10 Vat the wavelength of 240 nm. Such an excellent spectral response suggests PTFP is capable for used in daily and disposable UV status assessment.

Single-fabrication-step Ge nanosphere/SiO2/SiGe heterostructures: a key enabler for realizing Ge MOS devices

We report channel and strain engineering of self-organized, gate-stacking heterostructures comprising Ge-nanosphere gate/SiO2/SiGe-channels. An exquisitely controlled dynamic balance between the concentrations of oxygen, Si, and Ge interstitials was exploited to simultaneously create these heterostructures in a single oxidation step. Single-crystalline (100)/(110) Si}_{1-x}Ge}_{x} shells with Ge content as high as x= 0.85/0.35 and with a compressive strain of 3%/1.5% were achieved. Our high Ge-content, highly-stressed SiGe shells feature a high degree of crystallinity, providing a “building block” for the fabrication of Ge-based MOS devices.

Short-channel BEOL ZnON thin-film transistors with superior mobility performance

This work reports the first experimental submicron and sub-100 nm ZnON TFTs with excellent performance. Field-effect mobility values as high as 55 and 9.2 cm2/V-s were measured from ZnON TFTs with channel lengths of 0.5 μm and 75 nm, respectively. Those are the highest values ever reported on oxide-semiconductor TFTs of comparable channel length. The results confirm ZnON TFTs as an effective building block for the construction of BEOL circuits integrated in a chip.

Short-channel ZnON thin-film transistors with film profile engineering

Short-channel zinc oxynitride (ZnON) thin-film transistors (TFTs) were fabricated based on the film profile engineering in combination with e-beam lithographical patterning. ZnON films were deposited using reactive magnetron sputtering in N₂/O₂ ambient and exhibit a Hall mobility of 95 cm²/V-s. A ZnON TFT with channel length of 147nm shows high on/off current ratio of 5×10⁷ and field-effect mobility of 9.1 cm²/Vs, which are superior or comparable to their counterparts of IGZO or ZnO TFTs.

Fabrication and RTN characteristics of gate-all-around poly-Si junctionless nanowire transistors

Short-channel gate-all-around (GAA) poly-Si junctionless (JL) nanowire (NW) transistors were fabricated using the control available through cost-effective I-Line lithographic patterning and spacer techniques. This scheme enables the production of GAA JL poly-Si NW transistors with channel length of as short as 120 nm and effective width of 49 nm, featuring significant improvement in subthreshold swing (SS) and transconductance (Gm). The shrunken channel allows us to monitor clear random telegraph noise (RTN) signals under a sufficiently large gate overdrive condition.