Waves of switching in thyristor-like structures (original) (raw)

Switching waves in asymmetric thyristor-like structures for incomplete gate turn off regime

Semiconductor Physics, Quantum Electronics and Optoelectronics

I.Introduction This paper is devoted to the control of the currentconducting region in a thyristor-like structure. Here, as well as before [1, 2] we refer to TLS as a certain P + npN + structure where two outer layers provide effective injection of their majority carriers into two inner layers (bases). One of the bases (base I) is gated. The gate transfers the controlling current into the base. This current squeezes the current-conducting region (the ON-region in fig. 1), and enlarges the OFF-region. The gated base is usually highly conducting in comparison with the second base (base II). In silicon controlled rectifiers (SCRs) [3], the gate current just turns the TLS on and off, while in lightemitting (LE) and lasing (L) thyristors the gate current can also control (or modulate) light emission [4, 5]. That is why we are interested in characteristics of stationary control of the ON-region (the position of the layer between the ON-and OFF-regions, called the ON/OFF-junction) as well as the speed of the ON/OFF-junction in the TLS. Our further consideration is based on the fact that the typical structures of LE thyristors [6, 7, 8] differ greatly from the structures of SCRs. LE thyristors should not

Three-dimensional model of gate current flow in thyristor. I. Description

IEEE Transactions on Electron Devices, 1990

The digital gate concept is one of the fundamental ways leading to improvement of the dynamic rates of a thyristor. The distribution of the current density of the gate-cathode junction along the edge of the gate contact must, however, be as uniform as possible. A numerical model which permits determination of this distribution, the initial turn-on area, and their dependence

Investigation of the lateral turn-on process of thyristors with an epitaxial p-base

In this paper, the effect of the p-base doping concentraticon NA on the spreading velocity us in power thyristors is examined. Chemical vapor deposition (CVD) techniques are used to produce the pbase layer, in order to change the p-base doping concentration and thickness independently. The results show a large reduction of us with growing pbase doping concentration. At a do,ping concentration higher than 5 X 1016/cm3 the spreading velocity follows a power law with an exponent of -0,9. The introduction of a sandwiched lowdoped player between the p*-base and the n-emitter slows down the plasnra propagation. The decrease of us, in both cases, is attributed to the reduction of the current gain pz of the n-p-n transistor with doping concentration. In Qrder to explain this behavior, a simple expression for the spreading velocity is derived, which relates the spreading velocity to the time constant of current rise fr and consequently to the feedback loop gain ( p~p z ) of the two transistor components. In this derivation, only the lateral drift current in the p-base is taken into account. It was found that us is given by usl / t , -In in good agreement with the experiment.

An experimental analysis of the dual gate emitter switched thyristor (DG-EST)

Solid-State Electronics, 1999

In recent years, various dual MOS gated thyristor structures have been proposed to improve the three pronged trade-o of forward voltage drop, turn-o time and forward biased safe operating area when compared to single gate devices. The dual gate emitter switched thyristor (DG-EST), with its unique thyristor current partitioning mechanism, has been reported to posses superior characteristics when compared to conventional single gate ESTs. In this paper, a detailed study of the device physics of operation of the DG-EST is presented, supported by two dimensional numerical simulations. Eects of variations in the¯oating emitter length, lifetime in the drift region and temperature on the forward voltage drop are experimentally observed. An analytical model predicting the maximum controllable current density (J MCC) of the DG-EST is reported and con®rmed through experimental measurements. The DG-EST is found to have a superior trade-o curve of on-state voltage drop versus turn-o time when compared to the conventional emitter switched thyristor (C-EST).

Analysis of the impact of non-1D effects on the gate switch-on current in 4H-SiC thyristors

Semiconductors, 2017

The impact of non-1D effects caused by the spread of the gate current in the base layer on the gate switch-on current in 4H-SiC thyristors is considered. It is shown that a new switching mechanism implemented in 4H-SiC thyristors results in the dependence of the gate switch-on current on the thyristor parameters, with this dependence being fundamentally different from that in conventional silicon thyristors.

Numerical simulation of the insulated base MOS-controlled thyristor

This paper is aimed at the analysis of the insulated base MOS-controUed thyristor (IBMCT) using numerical simulations. This power device is composed of a vertical thyristor structure, two MOS gates (on-gate and off-gate) and a floating ohmic cont;tct (FOC). Transient simulations confirm the turn-off capabihty, and show that holes are diverted from the p-base to the FOC during the turn-off process. The electrical characteristics have been compared with those of the shorted .anode IBMCT. It is pointed out that this last structure is significantly faster than the IBMCT because the shorted anode provides a direct path for the extraction of the electron charge excess existing in the drift region during the turn-off process.