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可靠性问题是GaN基HEMT器件走向实用化的关键,逆压电效应导致器件退化是近年来比较引人瞩目的理论之一。对于GaN基HEMT器件,当其承受外加电场时,由于逆压电效应,电场最终转化成弹性势能。当电场足够大,突破势垒层材料所能承受的临界弹性势能,势垒层材料就会发生松弛。根据逆压电效应导致器件退化机理,从弹性势能的角度出发,对低Al组分AlGaN势垒层、InAlN势垒层和AlGaN背势垒等三种结构进行理论分析。分析表明,三种结构均能较大程度地改善GaN基HEMT器件的抗逆压电能力,从而提高器件可靠性。
Reliability is the key to the practical application of GaN-based HEMT devices. The inverse piezoelectric effect leads to device degradation is one of the more remarkable theories in recent years. For GaN-based HEMT devices, the electric field eventually transforms into elastic potential energy due to the inverse piezoelectric effect when it is subjected to an applied electric field. When the electric field is large enough to break through the critical elastic potential energy that the barrier material can withstand, the barrier layer material will relax. According to the mechanism of device degeneration caused by inverse piezoelectric effect, three structures of AlGaN barrier layer with low Al composition, InAlN barrier layer and AlGaN back barrier are theoretically analyzed from the perspective of elastic potential. The analysis shows that all the three structures can greatly improve the anti-stress piezoelectricity of GaN-based HEMT devices and improve the device reliability.