Hongyu He

The drain current modeling of antiambipolar thin film transistors (TFTs) in subthreshold and above-threshold regimes is presented. The drain current expressions of the n-type and p-type unipolar TFTs are extended to describe the electron current and hole current for antiambipolar TFTs, respectively. Applying the rule “smaller than the smallest” with the drain–source voltage-dependent empirical parameter, the drain current model for the antiambipolar TFTs is developed. The model is implemented in the circuit simulator using the Verilog-A programming language. A ternary inverter, which consists of antiambipolar TFT, p-type unipolar TFT, and n-type unipolar TFTs, is demonstrated.

Four-layer hexagonal silicon carbide (4H-SiC) is a promising material for high-temperature and radiation-rich environments due to its excellent thermal conductivity and radiation resistance. However, real 4H-SiC crystals often contain Shockley-type stacking faults (SSF), which can affect their radiation resistance. This study employed molecular dynamics (MD) simulation method to explore the effects of SSF on radiation displacement cascades in 4H-SiC. We conducted a comprehensive study of various SSF within the crystalline framework of 4H-SiC, and analyzed their stacking fault energy (SFE). We simulated the radiation displacement cascade in 4H-SiC with SSF and analyzed the effects of SSF on the distribution of radiation displacement defects. We simulated the radiation displacement cascade in 4H-SiC with SSF under different energies of primary knock-on atom (E_PKA) and temperatures (T) conditions, and analyzed the variation pattern of the number of radiation displacement defects and clusters. The results indicated that SSF limits defect distribution position. SSF has an effect on the defects and clusters of 4H-SiC in the displacement cascade, and SSF can affect the maximum working temperature of 4H-SiC.

A drain current model is presented for antiambipolar organic thin-film transistors (OTFTs) at different temperatures. Considering the temperature-dependent exponential distributed trap states density in energy gap of organic semiconductor, and analyzing electron and hole linear and saturation regimes, a drain current model is presented. The model can describe two-slope Arrhenius dependence in the drain current (with higher steepness at high temperature and reduced steepness at low temperature). The current peak and the gate voltage for current peak are investigated.

A current model is presented for forward-biased organic diodes at both high temperatures and low temperatures. The classical current model, which consists of two parts: the exponential-trap-based space-charge-limited current (SCLC) model in the high-voltage regime and the Ohmic current model in the low-voltage regime, can describe the Arrhenius-dependent current at high temperatures, but cannot describe the non-Arrhenius-dependent current at low temperatures. Introducing effective temperatures, the current model is presented. The presented model can describe both Arrhenius-dependent current at high temperatures and non-Arrhenius-dependent current at low temperatures. In particular, the presented model is compared with the well-known universal curve equation.

A voltage-programmed pixel circuit is presented for active-matrix organic light-emitting diode (AMOLED) displays. The circuit is made up by six p-type low temperature poly-silicon (LTPS) thin-film transistors (TFTs) and two capacitors (6T2C). In the extraction stage, the circuit extracts the driving TFT's threshold voltage and the power supply voltage. In the data input stage, the circuit generates a charging voltage, which is associated with the driving TFT's mobility and OLED's threshold voltage. Consequently, the pixel circuit not only compensates for the TFT's electrical characteristics variations, i.e., the threshold voltage and mobility variations, but also compensates for the voltage drop and the OLED degradation. The circuit simulation results show that the OLED current error rates (CERs) are lower than 7.13% when the threshold voltage varies ±0.5V, lower than 4.89% when the mobility varies ±30%, and lower than 8.92% when the voltage drop varies −0.5V.

Irradiated In _0.32 Ga _0.68 N in previous research showed temperature-dependent changes in Raman spectra, which indicates the crucial role of temperature in the evolution of cascades. To reveal the atomic-scale reason for temperature-dependent changes in Raman spectra, this paper investigates the overlapping cascades in irradiated In _0.25 Ga _0.75 N and In _0.32 Ga _0.68 N at different temperatures with the molecular dynamics method. The presented results indicate that defects in irradiated samples at elevated temperatures experienced enhanced atomic recombination in overlapping cascades. The temperature-dependent defects in In _0.32 Ga _0.68 N relate to the temperature-dependent shift of peaks A ^LO ₁ and E ^LO ₁ in Raman spectra by the LO phonon-plasmon coupling. The distribution of Ga clusters, N clusters, and In clusters is expected to have additional effects on localized electron carrier concentration which further influences the wavenumbers of peaks A ^LO ₁ and E ^LO ₁ in Raman spectra. The presented results provide academic support for reducing the defect production rate of the ion implantation doping technique at elevated temperatures.

A surface-potential-based drain current model is presented for ambipolar organic thin-film transistors (OTFTs). First, following the multiple trapping and release (MTR) conduction mechanism, a drain current model is presented for unipolar OTFTs considering exponentially distributed trap state density in the energy gap of an organic semiconductor. Next, from the model for unipolar OTFTs, analyzing electrons or (and) holes in different regimes, the model for ambipolar OTFTs is presented. The presented model can describe the drain current by compact expressions and can estimate the trap states density. The model is verified by available experimental data considering temperature characteristics.

Since its discovery, graphene has attracted widespread interest as a two-dimensional material composed of carbon atoms. It has a unique lattice structure and excellent properties, including high electrical conductivity, excellent carrier mobility, outstanding optoelectronic properties, excellent mechanical properties, chemical stability, and thermal conductivity. This makes graphene a great potential in the field of electrical and electronic devices. Graphene can be used in high-speed electronic devices, high-performance transistors, flexible displays, solar cells, photo detectors, and light sensors. This paper introduces the structure, properties, preparation, and characterization methods of graphene and its application in electrical and electronic fields, and summarizes its application potential and challenges in this field. All in all, graphene, as a material with unique properties, has broad application potential in the field of electronic and electrical devices and provides new opportunities for the development of electronic technology.