Hybrid La2O3-cPVP Dielectric for Organic Thin Film Transistor Applications

In this work, we have studied the electrical performance of cross-linked polyvinyl phenol (cPVP) modified lanthanum oxide (La2O3) bilayer dielectric film in pentacene thin film transistors (TFT). A simple spin-coating and room temperature operated cross-linking reaction of the hydroxyl moieties of PVP and the nitrogen groups of PMF were carried out to form the cross-linked PVP. The deposition of a thin 30 nm cPVP layer over the La2O3 layer provided a low leakage current (<10−7A/cm2), causing a reduction in the interface trap density. Besides, the modified surface properties of the La2O3 layer were favorable for the growth of pentacene organic semiconductors. As a result, the current on-off ratio and the sub-threshold slope was improved from 104 and 1.0 V/decade to 105 and 0.67 V/decade. The La2O3∕cPVP pentacene TFT operated at −10 V also exhibited improvement in the field-effect mobility to 0.71 cm2/Vs from 0.48 cm2/Vs for the single-layer La2O3 (130 nm) device. Thus, our work demonstrates that the rare earth oxide La2O3 with cPVP is an excellent dielectric system in the context of emerging transistors with hybrid polymer gate dielectrics.

Large-size (1.7 × 1.7 mm2) β-Ga2O3 field-plated trench MOS-type Schottky barrier diodes with 1.2 kV breakdown voltage and 109 high on/off current ratio

We fabricated high forward and low leakage current trench MOS-type Schottky barrier diodes (MOSSBDs) in combination with a field plate on a 12 μm thick epitaxial layer grown by halide vapor phase epitaxy on β-Ga2O3 (001) substrate. The MOSSBDs, measuring 1.7 × 1.7 mm2, exhibited a forward current of 2 A (70 A cm−2) at 2 V forward voltage and a leakage current of 5.7 × 10–10 A at −1.2 kV reverse voltage (on/off current ratio of > 109) with an ideality factor of 1.05 and wafer-level specific on-resistance of 17.1 mΩ · cm2.

High polarization and wake-up free ferroelectric characteristics in ultrathin Hf0.5Zr0.5O2 devices by control of oxygen-deficient layer

The formation of an interfacial layer is believed to affect the ferroelectric properties in HfO2 based ferroelectric devices. The atomic layer deposited devices continue suffering from a poor bottom interfacial condition, since the formation of bottom interface is severely affected by atomic layer deposition (ALD) and annealing process. Herein, the formation of bottom interfacial layer was controlled through deposition of different bottom electrodes (BE) in device structure W/HZO/BE. The transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses done on devices W/HZO/W and W/HZO/IrOx suggest the strong effect of IrOx in controlling bottom interfacial layer formation while W/HZO/W badly suffers from interfacial layer formation. W/HZO/IrOx devices show high remnant polarization (2Pr) ~ 53 µC/cm2, wake-up free endurance cycling characteristics, low leakage current with demonstration of low annealing temperature requirement as low as 350°C, valuable for BEOL integration. Further, sub-5 nm HZO thicknesses-based W/HZO/IrOx devices demonstrate high 2Pr and wake-up free ferroelectric characteristics, which can be promising for low power and high-density memory applications. 2.2 nm, 3 nm, and 4 nm HZO based W/HZO/IrOx devices show 2Pr values 13.54, 22.4, 38.23 µC/cm2 at 4 MV/cm and 19.96, 30.17, 48.34 µC/cm2 at 5 MV/cm, respectively, with demonstration of wake-up free ferroelectric characteristics.

RF/Analog and Linearity Performance Evaluation of Lattice-Matched ultra-thin AlGaN/GaN Gate Recessed MOSHEMT with Silicon Substrate

In this article, the Authors have demonstrated and analyzed various analog/RF and linearity performance of a AlGaN/GaN gate recessed MOSHEMT (GR-MOSHEMT) grown on a Si substrate with mathematical modeling based TCAD simulation. Specifically, a Al2O3 dielectric GR-MOSHEMT has shown tremendous potential in terms of AC/DC figure of merits (FOM’s) such as low leakage current, high transconductance, high Ion/Ioff current ratio and excellent linear properties corresponding to conventional AlGaN/GaN HEMT and MOSHEMT. The figure-of-merit metrics such as VIP2, VIP3, IIP3 and IDM3 are performed for different drain to source voltages (VDS) of 2.5V, 5V and 10V. All the modeling and simulation results are generated by Commercial Silvaco TCAD and found to be satisfactory in terms of high frequency and power applications. The present GR-MOSHEMT device shows a superior performance with a threshold voltage of 0.5V, Current density of 888 mA, high transconductance of 225 mS/mm and high unit gain cut-off frequency of 0.91GHz. The results of the developed AlGaN/GaN GR-MOSHEMT considerably improves the device performance and also suitable for high power distortion less RF applications.

Electrophysical characteristics of germanium MIS structures with rare-earth element fluorides

The electrical properties of MIS structures with rare-earth element fluorides on germanium substrates were studied to analyze the possibility of using these materials as gate dielectrics of devices. The structures are also studied from the point of view of assessing the degradation of their electrophysical properties under the action of electric fields of ~108 V/m, which act on the dielectric during electroforming, since the MIS structures with rare-earth element fluorides have the property of bistable switching. Studies of the I-V and C-V characteristics show that all structures have approximately the same value of the density of surface states at the rare-earth element / Ge fluoride interface. The leakage currents in the MIS structures with TmF3 and SmF3 film are less than in the MIS structures with NdF3 film of greater thickness. There is also no effect of reducing the current density when using the double film structure CeF3/DyF3. The most promising material with a low leakage current at a fairly high value of the dielectric constant in germanium MIS structures is thin-film samarium fluoride.