Specific features of the switch-on gate current and different switch-on modes in silicon carbide thyristors

• Published in: Semiconductor science and technology Vol. 29; no. 12; pp. 125012 - 125018
• Main Authors: Yurkov, S N, Mnatsakanov, T T, Levinshtein, M E, Cheng, L, Palmour, J W
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.12.2014
• Subjects: gate triggering; power devices; silicon carbide; thyristors
• ISSN: 0268-1242; 1361-6641
• DOI: 10.1088/0268-1242/29/12/125012

The specific features of the temperature and bias dependences of the switch-on gate current in SiC thyristors are examined analytically for two possible switching mechanisms. The so-called γ-mechanism, which is highly typical of the conventional Si thyristors, is characterized by very weak temperature and bias dependences. By contrast, the so-called -mechanism, which is very characteristic of SiC thyristors, is highly sensitive to changes in temperature and bias. If the thyristor is switched on by the -mechanism, the switch-on gate current density decreases very steeply with increasing temperature. As a result, the thyristor can lose its working capacity at elevated temperatures due to the instability against even very weak impacts. With decreasing the bias voltage Ua, the gate switch-on current increases very steeply, which can make switching the thyristor on difficult. The unintentional shunting, which is apparently present in high-voltage SiC thyristors, causes the transition from the - to the γ-mechanism at elevated temperatures and high biases. It can be supposed that introduction of a controllable technological shunting of the emitter-thin base junction allows stabilization of the temperature and bias parameters of SiC thyristors. The analytical results are confirmed by computer simulations performed in wide temperature and bias ranges for a 4H-SiC thyristor of the 18 kV class.