Silicon carbide of 4H-SiC type Schottky diode current-voltage characteristics in small-sized type metal-polymeric package SOT-89

The forward and reverse current–voltage characteristics of Ti/Al/4H-SiC Schottky diode type DDSH411A91 in modern small-sized (SOT-89) type metal-polymeric package have been obtained. In forward direction (current up to 2 A) on the basis of analysis it is shown that Schottky diode corresponds to the "ideal" diode with ideality factor n=1.12 and effective Schottky barrier height φB =1.2 eV. It is shown that reverse current-voltage characteristics (breakdown voltage 1200 V) can be well approximated by mechanism of field dependence of barrier height lowering by the presence of the intermediate layer in the form of oxide on the 4H-SiC surface.

Production and Electrical Properties of a CuZnAlMn(SMA)/p-Si Diode

In this study, the Cu-23.37%Zn-13.73%Al-2.92%Mn (at.%) alloy was used. Phase identification was performed with the Scanning electron microscope (SEM), and energy-dispersive X-ray (EDX). We observed in the austenite phase in Cu-23.37%Zn-13.73%Al-2.92%Mn (at.%) alloy. To produce a new Schottky diode, CuZnAlMn alloy was exploited as a Schottky contact on p-type semiconductor silicon substrate. To calculate the characteristics of the produced diode, current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G-V) analyzes were taken at room temperature (300 K), in the dark and under various lights. Using electrical measurements, the diode's ideality factor (n), barrier height (Φb), and other diode parameters were calculated. Besides, the conductance / capacitance-voltage (G/C-V) characteristics of the diode were studied and in a wide frequency interval at room temperature. Also, the capacitance and conductance values strongly ​​ rely on the frequency. From the present experimental results, the obtained diode can be used for optoelectronic devices.

Effects of Pulsed and DC Body-Diode Current Stress on the Stability of 1200-V SiC MOSFET I-V Characteristics

1,200-V and 1,700-V SiC power MOSFETs from multiple suppliers were subject to dc and pulsed-current stress of the body-diode. Three of the five suppliers of 1,200-V devices evaluated showed no significant bipolar degradation, but the other two supplier’s devices showed varying degrees of degradation due this bipolar phenomenon. Electrical results of newly released 1,700-V devices from two suppliers showed significant degradation in the body-diode and MOSFET I-V characteristics following both dc and pulsed-current stress of their body-diodes. The electrical results presented in this work are consistent with basal plane dislocations (BPDs) that form stacking faults during forward conduction of the body-diode. Significant drift in the body-diode forward voltage and MOSFET on-resistance indicates that a much higher BPD density may be present in 1,700-V devices in comparison to the more mature 1,200-V device offerings. The likely presence of BPDs can lead to significant reliability issues in some modern SiC power MOSFETs, and their distribution seems to vary across suppliers and among devices with the same rating and from the same supplier. These differences are likely due to variations in wafer and device processing among suppliers and within a given product line from a single supplier.

Hafnium dioxide effect on the electrical properties of M/n-GaN structure

In the present paper, using of SILVACO-TCAD numerical simulator for studying the enhancement in Pt/n-GaN Schottky diode current–voltage (I-V) characteristics by introduction of a layer of hafnium dioxide (HfO2) (with a thickness e = 5 nm) between the Pt contact and semiconductor interface of GaN is reported. The simulation of I-V characteristics of Pt/n-GaN was done at a temperature of 300 K. However, the simulation of Pt/HfO2/n-GaN structure was performed in a temperature range of 270 – 390 K at steps of 30 K. The electrical parameters: barrier height (Φb), ideality factor and series resistance have been calculated using different methods: conventional I-V, Norde, Cheung, Chattopadhyay and Mikhelashvili. Statistical analysis showed that the metal-insulator-semiconductor (Pt/HfO2/n-GaN) structure has a barrier height of 0.79 eV which is higher compared with the (Pt/n-GaN) structure (0.56 eV). The parameters of modified Richardson (\left( {\ln \left( {{{{{\rm{I}}_0}} \over {{{\rm{T}}^{\rm{2}}}}}} \right) - \left( {{{{{\rm{q}}^2}\sigma _{{\rm{s}}0}^2} \over {2{\rm{k}}{{\rm{T}}^2}}}} \right) = \ln \left( {{\rm{AA*}}} \right) - {{{\rm{q}}{\emptyset _{{\rm{B}}0}}} \over {{\rm{kT}}}}} \right) equation versus ({1 \over {{\rm{kT}}}}) have been extracted using the mentioned methods. The following values: {\rm{A}}_{{\rm{Simul}}}^* = 22.65\,{\rm{A/c}}{{\rm{m}}^{\rm{2}}} \cdot {{\rm{K}}^2}, 14.29 A/cm2 K2, 25.53 A/cm2 K2 and 21.75 A/cm2 K2 were found. The Chattopadhyay method occurred the best method for estimation the theoretical values of Richardson constant.

Optimization of p-type contacts to InGaN-based laser diodes and light emitting diodes grown by plasma assisted molecular beam epitaxy

We investigated the influence of the In0.17Ga0.83N:Mg contact layer grown by plasma assisted molecular beam epitaxy on the resistivity of p-type Ni/Au contacts. We demonstrate that the Schottky barrier width for p-type contact is less than 5 nm. We compare circular transmission line measurements with a p-n diode current-voltage characteristics and show that discrepancies between these two methods can occur if surface quality is deteriorated. It is found that the most efficient contacts to p-type material consist of In0.17Ga0.83N:Mg contact layer with Mg doping level as high as 2 × 1020 cm–3.

Impact of RbF-PDT on Cu(In,Ga)Se2 solar cells with CdS and Zn(O,S) buffer layers

Alkali-fluoride post-deposition treatments (PDTs) of Cu(In,Ga)Se2 (CIGS) absorbers have repeatedly resulted in device efficiency improvements, observed mainly due to an open-circuit voltage (Voc) enhancement. Replacement of the CdS buffer layer with a higher band gap alternative can increase the short-circuit current density (Jsc) and also eliminate the use of Cd. In many alternative-buffer attempts, however, the Jsc gain was accompanied by a Voc loss, resulting in some degree of performance loss. In order to better understand the impact of RbF-PDT, we analyze a combination of experimental devices produced in the same in-line CIGS run with and without RbF-PDT in combination with chemical-bath-deposited CdS and Zn(O,S) buffers. Low-temperature current–voltage curves indicate a difference in Rb impact on the CIGS/CdS and CIGS/Zn(O,S) p-n junctions. For example, the diode-current barrier which creates a rollover often observed in RbF-treated CIGS/CdS current–voltage curves is significantly reduced for the CIGS/Zn(O,S) junction. Although the RbF-PDT had a positive impact on both junction partner combinations, the CIGS/Zn(O,S) devices' Voc and fill factor (FF) benefited stronger from the RbF treatment. As a result, in our samples, the Jsc and FF gain balanced the Voc loss, thus reducing the efficiency difference between cells with CdS and Zn(O,S) buffers.

Power Efficiency Improvement of Three-Phase Split-Output Inverter Using Magnetically Coupled Inductor Switching

The conventional three-phase split-output inverter (SOI) has been used for grid-connected applications because it does not require dead time and has no shoot-through problems. Recently, the conventional inverter uses the silicon carbide (SiC) schottky diodes for the freewheeling diodes because of its no reverse-recovery problem. Nevertheless, in a practical design, the SiC schottky diodes suffer from current overshoots and voltage oscillations. These overshoots and oscillations result in switching-power losses, decreasing the power efficiency of the inverter. To alleviate this drawback, we present a three-phase SOI using magnetically coupled inductor switching technique. The magnetically coupled inductor switching technique uses one auxiliary diode and coupled inductor for each switching leg in the three-phase SOI. By the operation of the coupled inductor, the main diode current is shifted to the auxiliary diode without the reverse-recovery process. The proposed inverter reduces switching-power losses by alleviating current overshoots and voltage oscillations of SiC schottky diodes. It achieves higher power efficiency than the conventional inverter. We discuss experimental results for a 1.0 kW prototype inverter to verify the performance of the proposed inverter.