An Accurate Switching Current Measurement Based on Resistive Shunt Applied to Short Circuit GaN HEMT Characterization

The use of a resistive shunt is one of the simplest and most used methods for measuring current in an electronic device. Many researchers use this method to measure drain current during short-circuiting of fast devices such as GaN HEMTs. However, the high switching speed of these devices together with the non-ideality of the shunt resistors produces an overestimation of the current in the initial phases of the transient. In this paper, a passive compensation network is proposed, which is formed by adding an inductor to the voltage measurement circuit and allows an accurate measurement of the current using the resistive shunt even in the presence of very fast devices. The proposed method is validated by simulations and experimental measurements.

Junctionless FETs On Silicon-On-Insulator With Buried Metal Fin For Multi Threshold Operation

In this paper, an n-channel junctionless FET (JLFET) based on SOI with a buried metal fin (BMF) is presented. We show that the BMF of suitable workfunction of the proposed device BMF-SOI-JLFET can control the channel electrostatic field by employing Schottky junction effectively. The enhanced association of potential between BMF and the channel combined with gate electric field makes it worthy for multi-threshold and dynamic threshold (DT) operation. Additionally, the biasing of BMF projects the broad range of threshold voltage (VTH­) regulation with a high value of body factor (γ). The proposed device demonstrates γ enhancement compared to fin body (FB)-JLFET and conventional SOI-JL FET under identical conditions due to constant potential coupling. The DT mode of operation shows a 73% improvement in ON-state current in addition to reduced subthreshold swing contrast to BMF-SOI-JLFET without DT. This paper imparts a viable option for low power applications with multi-threshold operation and high switching speed applications with DT operation.

An Improved Analytical Model for Crosstalk of SiC MOSFET in a Bridge-Arm Configuration

SiC MOSFETs have an excellent characteristic of high switching speed, which can improve the efficiency and power density of converters significantly. However, the fast switching processes of SiC MOSFETs cause serious crosstalk problems in bridge-arm configurations, which restricts the devices’ performances. This paper presents a detailed and accurate improved crosstalk analytical model, which takes into account the nonlinear capacitances, the parasitic inductances, the reverse recovery characteristics of the anti-parallel diodes, and the nonlinear voltage switching and damping oscillation process. The novelty of the proposed model lies in the fact that under the condition of comprehensively considering all these non-ideal factors of the bridge-arm, the effects of multi-parasitic elements and multi-variables coupling to the crosstalk are hierarchically divided. The parasitic elements and their correlations are described in detail and the direct and indirect variables’ impacts are clearly traced. Thus, according to the different variables switching stages, the influence processes of these parasitic elements and variables can be integrated and a complete equivalent analytical model of the crosstalk process can be derived. The simulation and experiment platforms are established and a series of experimental verifications and comparisons prove that the model can replicate experimental measurements of crosstalk with good accuracy and detail.

A memory nanodevice based on Zn-MOF-74: a molecular dynamics study

C60−@Zn-MOF-74 operated by an electric field exhibits a combined high switching speed of 27 GB s−1 and a high memory element density of 106 Tb per inch2.

Effects of Very High Workfunction Metals or Metal Alloys (NiCr) on High Switching Speed, HV Schottky Diodes for Mixed Signal or RF ASIC

For high switching speed HV Schottky diodes, with very high work function metal and extremely lightly doped epi, the built-in potential may be too high for thermionic emission to occur, when the applied external voltage is quite low (near VF = 0.07V). If the epi is lightly doped p type, the built-in potential (VBuilt-in: potential difference between the metal and silicon Fermi levels) is 1.0V (measured with CV). If the external bias is 0.1V, near the measured VF, it is not enough to overcome the built-in potential for thermionic emission as illustrated. It is likely that in addition to thermionic emission, tunnelling and diffusion currents also contribute to the total HV Schottky diode forward current. TCAD simulation of HV Schottky diodes with N+ guard bands suggests the potential barrier and electric fields at the Schottky junction are relatively high for thermionic emission to occur, when external bias V ≈ VF. In this paper we report HV Schottky diodes fabricated with various metals, metal alloys and epitaxial films. Metal work functions and epi doping profiles are extracted with high frequency Capacitance-Voltage (CV) technique. 150V of breakdown voltage and very low forward voltage (VF = 0.07V) are demonstrated. The measured data indicate very high work function metal or metal alloy is needed to achieve high switching speed and low forward voltage.